Homelessness Feasibility study - Causes of Homelessness and Rough Sleeping - GOV.UK

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MARCH  2019 | Rough sleeping feasibility Study
    Homelessness

                   Homelessness
                            Causes of Homelessness and Rough Sleeping

                                 Feasibility study

                                                                        Page 1 of 84
Homelessness | Feasibility Study

               Homelessness
                         Causes of Homelessness and Rough Sleeping

                               Feasibility study

                                                                     Page 2 of 84
Homelessness | Feasibility Study

Table of Contents

Non-technical summary .......................................................... 4
1. Scope ................................................................................. 8
   1.1 Overview and aims ................................................................................................................ 8
   1.2 Purposes of the model suite .................................................................................................. 9
   1.3 Modelling options ................................................................................................................ 13

2. Collections of data ............................................................ 17
   2.1 Overview .............................................................................................................................. 17
   2.2 Evidence gaps and areas for improvement ......................................................................... 18

3. Key choices for designing a homelessness model suite .... 31
   3.1 Model development ............................................................................................................. 31
   3.2 Ease of use .......................................................................................................................... 33
   3.3 Flexibility .............................................................................................................................. 34
   3.4 Granularity of outputs .......................................................................................................... 35
   3.5 Transparency ....................................................................................................................... 36

4. Considerations of model specific issues ............................ 38
   4.1 Time-series models.............................................................................................................. 38
   4.2 Simulation models ............................................................................................................... 42

5. Conclusions and recommendations .................................. 54
References ........................................................................... 57
Appendix: Data overview ...................................................... 58
   A.1 Existing data sources .......................................................................................................... 58
   A.2 Upcoming homelessness data collections .......................................................................... 80

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Non-technical                                                         o appraise the impact of suggested
                                                                        policy changes.

summary                                                               Key choices for the development
                                                                      of a suite of models on
                                                                      homelessness
The feasibility study explores a set of
available options for a suite of models                               The key message from assessing the
on homelessness and rough sleeping                                    characteristics of different classes of
in England. This is part of a three                                   models on homelessness is that each
series project that includes a rapid                                  model class has specific aspects that
evidence assessment of                                                render it more suitable for certain
homelessness and rough sleeping                                       purposes than others. Based on this
causes in the UK and abroad as well                                   finding, we recommend the
as a review of existing models on                                     development of a suite of different
homelessness. Key findings from                                       models to address each distinct
these strands of research inform drive                                objective rather than a single, multi-
our recommendations for developing                                    purpose model. The suggested suite
models to estimate future trends in                                   should include the following:
homelessness and rough sleeping and
                                                                      o time-series models for accurate
appraise government policies.
                                                                        short-term forecasts
Specifically, the models could be used                                o simple, ad-hoc simulation models
by analysts in the Ministry of Housing,                                 for appraisal of specific policies
Community and Local Government
(MHCLG) and the Department for                                        o complex simulation models for
Work and Pensions (DWP) to address                                      medium to long term projections of
the following objectives:                                               homelessness types conditional on
                                                                        a broad set of predictive factors
o generate accurate short-term                                          that are shown in the literature to
  forecasts of various types of                                         influence homelessness.
  homelessness including statutory
  homelessness,1 single people                                        Time series models
  homelessness and rough sleeping
                                                                      The optimal solution for predicting
o project medium to long term trends                                  levels of homelessness and rough
  in various types of homelessness                                    sleeping in the short-term is the
                                                                      development of time series models
                                                                      that are empirically shown to generate

11                                                                       putting this report into context, we use the term
   Under
   UnderthetheHomelessness
                HomelessnessReduction
                                   Reduction  Act
                                                Act2017,
                                                     2017, the definition     of statutory   homelessness
                                                                         ‘statutory  homelessness’     to referhas  been
                                                                                                                to the former
the  definition
 recently       of statutory
           extended            homelessness
                        to include             has people
                                     all homeless    been (includingofficial
                                                                           singledefinition
                                                                                   homeless     and  those  in hidden
                                                                                            (i.e. homeless households in
recently  extended
 homelessness)        to include
                    who   turn to all  homeless
                                   Local          people
                                          Authorities    for homelessness       and
                                                                         priority   rough
                                                                                  needs     sleeping
                                                                                          that apply toservices.   For ease of
                                                                                                         LAs for temporary
(including
 referencesingle
              and tohomeless
                      avoid any  and  those in hidden
                                   confusion   when putting this report       into context,    we  use the  term  ‘statutory
                                                                         accommodation), which is still universally used in
homelessness)
 homelessness’who        turn to the
                    to refer      Local  Authorities
                                      former  officialfor
                                                        definition (i.e. homeless    households
                                                                         the literature             that are and
                                                                                        on homelessness       accepted
                                                                                                                   rough as
                                                                                                                         sleeping
 homeless andand
homelessness       in priority  need by services.
                       rough sleeping     LAs, whichForis still universally   used in the literature on homelessness and
                                                                         in England.
 roughofsleeping
ease     referenceinandEngland.
                           to avoid any confusion when

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accurate predictions in the near future.   trends. However, the development of
The models are simple in that they         such a model is a long-term process
arrive at short-term forecasts based       that requires high levels of expertise
on historical trends and are not           and substantial investment in
dependent on factors that are shown        resources.
to predict or cause homelessness and
rough sleeping. While there are            In the short-term, we suggest the
versions of time series models that        development of simple, ad hoc
include a set of predictive factors and    simulation models to provide timely
can be used to evaluate the impact of      evidence-based assessments of future
policy changes, they are not an            policies. These simpler versions of
optimal method for policy appraisal as     economics-based simulation models
they won’t correctly identify the          can be used to help quantify the net
relationships from predicting factors to   effects from introducing new policies
homelessness.                              without having to consider baseline
                                           trends in homelessness (in the
Simulation models                          absence of the policy) and the factors
                                           that drive them.
Economics-based simulation models
project outcomes of interest               Data inputs and model elements
conditional on a set of predictive
factors. They are based on a solid         The rapid evidence review of the
theoretical framework that allows for      causes of homelessness and rough
modelling homelessness and rough           sleeping revealed that homelessness
sleeping as the outcome of complex         is a complex phenomenon that
relationships between a broad set of       emerges as a result of intricate
predicting factors. In theory, the         interactions between a broad set of
models can produce short-term              policy, economic and personal factors.
predictions – however, their outputs       Policy analysts can choose the set of
depend on estimated future trends          predictive factors that should be
and potential relationships between a      included in the models based on the
broad set of determinants that are         model’s objectives.
likely to materialise in the medium to     For example, time series models can
long term. Therefore, these type of        generate forecasts simply by using
models are better placed for               historical series of data for the variable
appraising policies and estimating         of interest. Simple ad hoc models can
long-term trends rather than               include a set of variables that are
producing predictions in the short-        relevant to the policy in question while
term.                                      more complex simulation models
In the long run, it is important that      usually integrate a number of modules
MHCLG and DWP can use complex              to model the links between outcomes
simulation models to conduct a             of interest and a broad set of
comprehensive analysis of the              explanatory factors.
mechanisms driving future
homelessness and rough sleeping

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The suggested models can be                   models on homelessness in England.
developed using existing sources of           Moreover, the literature suggests that
data on homelessness and predictive           experiences of homelessness differ
factors – i.e. administrative sources of      across vulnerable groups. Therefore, it
data on homelessness and rough                is important to understand the impact
sleeping collected by LAs, data from          of national policies on different
surveys that are either centred around        segments of the population (e.g. low-
homelessness or include relevant              income households, victims of
information, and official statistics for      domestic violence, immigrants, people
predictive factors. However, better           with mental health and drug abuse
data can result in more reliable              problems).
outputs using the same methodology.
For example, more granular and                It is important that the suite of models
precise estimates of different types of       can produce highly granular outputs
homelessness can be achieved if the           across different levels of geographic
following data improvements are               disaggregation (e.g. regions, local
realised:                                     authorities), types of homelessness
                                              that are driven by different underlying
o covering different types of                 factors (e.g. sofa surfers, concealed
  homelessness (e.g. sofa-surfing,            homelessness) and population groups.
  overcrowding),                              The entire set of components of the
                                              model suite should be developed
o linking data from various sources,
                                              using detailed data that allow for
  and
                                              disaggregation at the geographical
o improving consistency and data              level and across different population
  sharing across LAs.                         segments.
As reliability of outputs depends on          Moreover, the suggested suite of
quality of available data, improvements       models should be easy to use and
in data on homelessness are                   maintain by in-house analysts. While
considered to be of equal priority to         the development of some elements of
development of robust models.                 the model suite could be externally
                                              commissioned (e.g. time series model
Key modelling choices                         and complex simulation model), the
                                              departments should be able to
Patterns of homelessness and rough
                                              operate, revise and update the entire
sleeping vary from place to place
                                              set of components of the model suite
across England and are likely driven by
                                              using their own resources and
interactions between a range of
                                              expertise.
different factors specific to each area.
In this context, it is likely that national   Documentation, including guidance for
policies around homelessness and              model applications as well as front
rough sleeping have different impacts         ends that will allow users to easily
throughout England. Therefore,                operate the models, should be
regional variation is a critical aspect to    provided along with the core models.
consider in developing a suite of             The departments should also invest

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time and resources to train in-house
analysts to revise and update the
models – for example, using updated
data or different assumptions about
key model parameters. It should be
noted here that developing an easily-
accessible front end and detailed
guide can often be as difficult and time
consuming as developing a model’s
core ‘engine’.
In the case of simulation models,
implementing a full modular structure
is important to ensure that even a
complex model can be accessible to
in-house analysts. A large model
should build in separate components
explicitly considering and planning for
future adjustments in the development
stage. It is important that the separate
modules are built in a consistent way
that allows different teams of analysts
to revise the model or add new
modules without having to change the
core model structure.
Finally, the development of a suite of
models that produces highly granular
outputs and considers the impact of
broad sets of determinants is a
demanding and long-term process.
Therefore, it is important that the
departments develop or retain the
expertise to design and use ad hoc
simulation models that consider a
limited set of links between predictive
factors and outcomes of interest to
conduct ex ante evaluation of potential
policy changes within limited time
frames.

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                                                                of models to predict homelessness
1. Scope                                                        trends in the future and appraise
                                                                planned changes in broad policy
                                                                areas. Available evidence regarding
                                                                data inputs, modelling options and
1.1 Overview and                                                explanatory factors will guide our
                                                                recommendations about the
aims                                                            development of methodologies
This feasibility study seeks to explore                         suitable for addressing distinct national
options for the development of a                                policy questions in the most effective
model, or a suite of models, that could                         way.
be used to assess the impacts of
                                                                Instead of focusing on a single and
Government intervention on levels of
                                                                complex model that can potentially
homelessness.
                                                                address all different objectives, we
This study is informed by three strands                         propose the development of a
of research that were conducted as a                            composite model suite that comprises
part of the wider feasibility project:2                         various components. In our
                                                                recommendations, we take into
o a rapid evidence assessment of the                            account an array of issues related to
  factors that cause various types of                           data inputs, outputs, resources,
  homelessness in the UK and                                    methodological considerations,
  overseas,                                                     modelling choices and types of
o a review and assessment of the                                policies that the models should
  suitability of existing methodologies                         consider.
  that have been applied to
                                                                This section outlines the purposes that
  accommodate different policy
                                                                the Ministry of Housing, Communities
  purposes related to homelessness,
                                                                and Local Government (MHCLG) and
  and
                                                                the Department for Work and
o an overview of existing data and                              Pensions (DWP) seek to
  recommendations regarding                                     accommodate by conducting
  potential areas of improvement for                            empirical research. Moreover, we
  data that feeds into homelessness                             identify and discuss a range of options
  models.                                                       for adapting approaches to address
The findings of these exercises provide                         these objectives. Section 2 maps
an evidence base for identifying                                existing sources of administrative and
available options for developing a suite                        survey data on homelessness as well
                                                                other types of data that can potentially

22                                                                  is presented in a separate report under the title
   Findingsfrom
  Findings   fromthethe  rapid
                      rapid      evidence
                             evidence        assessment
                                         assessment    on on causes of homelessness are presented in a separate
                                                                    “Review of Homelessness Models”. The overview of
 report of
causes   under  the title “Rapid
           homelessness              EvidenceinAssessment”.
                             are presented       a             The review and assessment of existing classes of
                                                                    existing data, evidence gaps and recommendations
 models report
separate  used to  predict
                 under    the and   measure
                              title “A         homelessness is presented in a separate report under the title
                                       Rapid Evidence               for potential areas for improvements in collections
 “Review of About
Assessment    models    ofCauses
                      the   homelessness”.      The overview of existing data, evidence gaps and recommendations
                                     of Homelessness”.              of data on homelessness is presented in section 2
 for review
The  potential
            andareas   for improvements
                 assessment                   in collections
                                  of existing classes of     of data on homelessness is presented in section 2 of
                                                                    of the current report.
 the current
models   used report.
              to predict and measure homelessness

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feed into homelessness models,             We will discuss the applicability of
summarises upcoming data                   different classes of models in
collections and highlights gaps in the     addressing these three distinct
evidence to make suggestions about         objectives for various types of
potential improvements in data             homelessness. Theoretically, a
collection. Section 3 discusses a set of   methodological approach applies
key modelling choices that apply to        equally well to all outcomes related to
the entire collection of models that       homelessness since these outcomes
should be developed while section 4        are measured by variables of the same
highlights modelling issues that are       type (e.g. continuous variables for
specific to the particular components      population counts, probabilities for
of the model suite. Finally, section 5     estimation of homelessness risks, etc.)
sets out recommendations and               For example, the same time series
considerations for developing a suite      model (e.g. Autoreggressive Integrated
of models to inform policies on            Moving Average – ARIMA – model)
homelessness.                              can handle different series of data
                                           inputs to forecast the entire range of
                                           homelessness types (for example,
1.2 Purposes of the                        inclusing single homeless, and sofa
model suite                                surfers) and rough sleeping. What
                                           might change across different types of
The model suite is meant to be used        homelessness are the assumptions
by MHCLG and DWP to address the            about model determinants in the
following set of objectives related to     sense that each homelessness type is
various types of homelessness and          likely to be driven by different mixtures
rough sleeping:                            of causal and predicting factors.
o short-term forecasting,                  Our objective is not just to recommend
o projections of medium to longer-         ways for producing forecasts and
  term trends, and                         projections for broad categories of
                                           homelessness such as statutory
o appraisal of hypothetical policy
                                           homelessness, single homeless and
  scenarios designed to influence
                                           people who sleep rough. Instead, we
  levels of homelessness.
                                           will identify a range of options for
The discussion is centred around the       generating outputs at different levels of
development of an empirical approach       disaggregation (e.g. new
to forecasting and projecting future       homelessness levels among former
levels of different types of               care leavers, homelessness among
homelessness types under baseline          black and minority ethnic (BME)
assumptions or alternative policy          groups, returns to rough sleeping
scenarios that are likely to affect        among people with complex needs).
homelessness (for example, policies
affecting the supply of housing or
levels of welfare support for housing
costs).

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       Box 1. Types of homelessness – a discussion about
       definitions

       According to the Office for National Statistics (ONS) and MHCLG, a
       household or an individual is considered homeless and can apply for
       homelessness support when they:
       “no longer have a legal right to occupy their accommodation or if it would
       no longer be reasonable to continue to live there, for example if living there
       would lead to violence against them”.
       Moreover, the official MHCLG definition for people who sleep rough is the
       following:
       People sleeping, about to bed down (sitting on/in or standing next to their
       bedding) or actually bedded down in the open air (such as on the streets,
       in tents, doorways, parks, bus shelters or encampments). People in
       buildings or other places not designed for habitation (such as stairwells,
       barns, sheds, car parks, cars, derelict boats, stations, or “bashes”).
       The rough sleeping definition does not include people in hostels or
       shelters, people in campsites or other sites used for recreational purposes
       or organised protest, squatters or travellers.
       Prior to the recent Homelessness Reduction Act 2017, the official
       definition of statutory homelessness comprised three criteria:
       o being eligible for assistance,
       o being unintentionally homeless – ‘intentionally homeless’ are
         considered the households that left a home that could have stayed in,
         and
       o falling within a specified priority need group – households with
         dependent children or a pregnant woman; individuals who are
         vulnerable as a result of mental illness or physical disbaility ; individuals
         aged 16-17 years old; individuals aged 17-19 who were previously in
         care; vulnerable individuals as a result of previously being in care, ΗΜ
         forces or under custody; vulnerable individuals who had to flee their
         home as a result of violence or threat of violence.

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       The Housing Act 1996 –provides that where an applicant meets the
       above three criteria, then local authorities (LAs) have a statutory duty to
       provide them with a settled home, and where this is not possible straight
       away, they are under a duty to provide suitable temporary
       accommodation until settled accommodation can be found. Counts of
       households and people that were in temporary accommodation
       following accepted homelessness applications were reported at the end
       of each quarter. National statistics on statutory homelessness were
       derived from these counts reported by LAs. While rejected applications
       for homelessness (either because households were found not to be in
       priority need or because they were considered to be intentionally
       homeless) were also reported, no other information on these groups that
       are considered to be non-statutory homeless was reported.
       According to MHCLG, there are three sub-groups in the non-statutory
       homelessness category:
       o single homeless,
       o people who sleep rough – people bedded down in the open air, and
       o hidden homeless – people who are homelessness but are not visible
         in official statistics (sofa-surfing).

       The new Homelessness Reduction Act 2017, which came into force in
       April 2018, leads to important changes in the delivery of homelessness
       services. Under the new Act, LAs are required to offer two new duties
       (prevention and relief) to all applicants that are eligible even if they are
       intentionally homeless or do not fall into any priority needs category.
       In this context, the new official definition for statutory homelessness has
       been broadened to include the entire range of single people and
       households that apply to the LAs for homelessness support (even if they
       are not eligible for temporary accommodation). Therefore, the new
       national statistics need to integrate figures on what previously was
       considered non-statutory homelessness in addition to rough sleeping.
       Developing a broader definition is critical for guiding collection of data
       that cover the entire range of homelessness types including statutory
       homelessness, rough sleeping, sofa surfing and concealed
       homelessness (‘over-crowding’).
       Bramley (2017) suggests the following two alternative definitions that are
       broader in the sense that they integrate forms of non-statutory
       homelessness that fall out of official statistics:

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      o Core homelessness that includes the most acute forms of
        homelessness (rough sleeping, sleeping in tents and cars, unlicensed
        and insecure squatting, unsuitable, non-residential accommodation,
        hostel residents, users of night/winter shelters, domestic violence
        victims in refuge, unsuitable temporary accommodation, sofa surfing),
        and
       o Wider homelessness that refers to people who are at risk of
         homelessness or stay in some form of temporary accommodation
         (staying with friends and relatives due to inability to find proper
         accommodation, eviction/under notice to quit, asked to leave by
         parents/relatives, intermediate accommodation and receiving support,
         in other temporary accommodation, discharged from prison, hospital
         or other state institution without permanent housing).
       Finally, efforts have been made to establish a harmonised official
       definition of homelessness across the UK. The Government Statistical
       Service (GSS) Harmonisation Team, which is part of ONS, has been
       recently commissioned by MHCLG to map the definitions of
       homelessness that are used in the UK and investigate options for
       developing a harmonised homelessness definition.
       It was found that different homelessness definitions reflect differences in
       homelessness policies and priorities in delivery of prevention and support
       services across the UK countries. Moreover, information regarding the
       comparability between different definitions appears to be limited.
       The GSS harmonisation team has further explored a set of
       homelessness definitions that are used across government bodies (e.g.
       MHCLG for national statistics on homelessness, DWP for those in need
       of benefits and the Ministry of Justice (MoJ) for assessing
       accommodation of ex-offenders) and non-government organisations (for
       example, core and wider homelessness definitions used for CRISIS
       projections of future trends in homelessness).
       Variations in homelessness legislation and operational differences when
       applying the definitions to produce homelessness statistics were also
       examined across UK countries.
       Findings from this research revealed that introducing a harmonised
       definition would require changes in legislation and data collections
       across the devolved nations that are not straightforward to implement.
       Therefore, the GSS harmonisation team recommended that a
       conceptual framework for homelessness should be created in order to
       map different definitions and data collections in the UK and improve
       comparability of existing statistics.

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                                          model that can address all purposes.
1.3 Modelling options                     Moreover, the development of a
Accounting for the complexity of the      complex comprehensive model
phenomenon under analysis and the         requires time and resources while
theory underpinning homelessness as       smaller models can be designed in the
well as distinguishing between the        short term to address immediate
distinct purposes of short-term           policy objectives. The design of small
forecasting, long-term projections and    ad hoc models can also be seen as a
policy appraisal are key considerations   critical step to the long-run process of
when developing models around             developing a robust complex
homelessness.                             simulation model that can be used for
                                          the entire set of policy purposes
For instance, the complexity of           associated with homelessness and
relationships between different factors   rough sleeping.
– such as the interconnections
between the housing and labour            For example, the CLG-Affordability
markets across English areas – that       model – a complex simulation model
influence homelessness levels is an       that estimates housing affordability in
important element that should be          England as the outcome of a number
considered when projecting long-term      of interconnected determinants
homelessness trends. However,             (NHPAU, 2009) – consists of a set of
including assumptions about such          simpler simulation models on house
relationships to estimate trends in the   prices as well as housing demand and
short-term is likely to result in         supply that can be used separately.
decreased forecasting accuracy.           These models have been also utilised
                                          in the development of the components
A key choice that needs to be made is     of the Sub-Regional Housing Market
between developing a single, large-       Model (SRHMM) developed by
scale and complex model that              Bramley and Watkins (2016).
integrates multiple features or a suite
of simpler models that are used to        In the review and assessment of
accommodate distinct purposes. A          classes of models that are used to
number of issues, including the           measure and predict homelessness,
applicability of the available            we identified a set of methodologies
methodologies as well as the costs        that can be applied to address policy
associated with each option, should       purposes around homelessness. The
be considered in informing the choice     key take-away from the model review
of the optimal strategy.                  and assessment is that there is merit
                                          to applying different models for
Specifically, the costs of developing     different purposes.
and using a large-scale, complex
model that integrates various features    As shown in figure 1, which
to model all possible links and           summarises the main findings of the
interdependencies between related         model review and assessment, each
factors and homelessness types might      class has particular statistical
exceed the benefits of having a single    properties that makes it more suitable

                                                                    Page 13 of 84
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for some purposes than for others. For                             Projections of trends under baseline
example, time-series models are                                    assumptions and evaluation of
simple trend-based methods that                                    changes in homelessness levels under
generate accurate forecasts of                                     alternative policy scenarios are
outcomes of interest in the short-term                             separate exercises.
based on the underlying assumption
that patterns that existed in the past                             Though these objectives can be
will continue into the future. While they                          covered within the same overall
can be applied to estimate medium to                               framework (for example, a simulation
longer-term trends, they lack the                                  model can do both), different versions
theoretical framework that is needed                               of models that fall within this class can
to account for relationships between                               be used to address these two distinct
explanatory factors and outcomes that                              objectives.
play out in the long-term.                                         Essentially, simple ad hoc models can
                                3
Based on our findings and the above                                be used to quantify the impact of
discussion, we recommend the                                       specific policies compared to a
development of a flexible suite of                                 baseline ‘do nothing’ scenario. The
models that will comprise a set of                                 estimation of additional effects from
methodologies applied to address                                   launching a new policy does not
different objectives instead of a                                  necessarily require considering the
complex, large-scale model.                                        baseline levels of homelessness and
Specifically, we suggest that models                               rough sleeping. SRHMM (Bramley and
from the following two broad classes                               Watkins, 2016) is an example of a
should be applied to accommodate                                   comprehensive simulation model that
MHCLG and DWP policy objectives:                                   projects housing needs, including
                                                                   homelessness, under composite
o time-series models for short-term                                policy and economic scenarios.
  forecasting,4 and
o economics-based simulation
  models for medium to long-term
  projections and policy appraisal.

3                                                                  figure 1, from
                                                                             machine    learningand
                                                                                                 techniques     arethe
                                                                                                                     anset of
3  Our recommendations
   Our  recommendationsfor    forsuitable
                                  suitablemodels
                                            models    are based on findings
                                                    are                             reviewing       assessing
 model   classes that  have   been   used  to predict   and measurealternative
                                                                     types  of  option for generating
                                                                                homelessness.     For a accurate
                                                                                                         detailed    short-
based on findings from reviewing and assessing the                 term
 discussion
set  of modelabout
              classesthethat
                          characteristics
                             have been used of existing  models, see
                                                to predict            theforecasts.
                                                                          “Review of  However,
                                                                                        model ofthe  reliability of machine
                                                                                                   homelessness”
 report.                                                           learning outputs relies on the amount and level of
and measure types of homelessness. For a detailed                  detail of data on homelessness. Therefore, applying
 4
discussion   aboutinthe
   As discussed      thecharacteristics
                          model reviewofand  existing
                                                shown in figure 1, such
                                                                   machine     learning
                                                                          models         techniques
                                                                                   to English         are ana alternative
                                                                                               data (facing     number of
models,   see
 option for   the “Review
            generating       of Homelessness
                          accurate   short-termModel”
                                                   forecasts. However,  the reliability
                                                                   limitations  that areof machineinlearning
                                                                                         discussed      sectionoutputs
                                                                                                                  2 of this
report.
 relies on the amount and level of detail of data on homelessness.          Therefore,
                                                                   report) is            applying
                                                                              likely to be         such models to
                                                                                           suboptimal.
4English data (facing a number of limitations that are discussed in section 2 of this report) is likely to be
   As discussed in the model review and shown in
 suboptimal.

                                                                                                          Page 14 of 84
Homelessness | Feasibility Study

     Box 2. Other policy objectives and methods to address
     them

     The following policy purposes can be also addressed by applying
     empirical models:
     o identifying homelessness risks for households and individuals and
       single people,
     o measuring homeless groups that are not straightforward to capture,
       and
     o evaluating existing policy interventions that address homelessness.

     The models used to accommodate these purposes include:
     o homelessness risk models,
     o non-standard sampling models such as the capture-recapture method,
       and
     o models developed to quantify intervention (treatment) effects for
       participants in the period following the intervention.

     The focus of this feasibility study is not to recommend ways to explicitly
     address these additional objectives. However, the above methods can
     potentially complement the main models developed to predict
     homelessness levels and appraise policies. For example, outputs from
     homelessness risk models can be integrated into larger and more
     complex policy models that simulate homelessness outcomes under
     different scenarios.
     Alternatively, these methods can be used as stand-alone policy tools
     developed outside the main models. It may be worthwhile for MHCLG to
     sponsor a project that brings together expertise from LAs that use
     homelessness risk models to develop a common approach to identifying
     households and single people that are in priority need for homelessness
     prevention services. Such an approach can also be adopted to assess
     differential impacts of the implementation of central policies in different UK
     regions. For example, policies around private rent prices (e.g. housing
     benefits) and housing supply (e.g. investment in council housing) are
     expected to exert significant impact on homelessness risks in London
     Boroughs where high private rents and shortages in supply of council
     housing are important drivers of homelessness. On the other hand, such
     policies are not expected to have a similar impact in Northern England
     where access to social housing does not appear to be a major issue
     (Fitzpatrick et al. 2018).

                                                                           Page 15 of 84
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       Capture-recapture methods, which use a set of sampling techniques to
       estimate the size of populations that are elusive and thus not
       straightforward to measure,1 can be implemented to guide new data
       collection that can improve the outputs of models. Alternatively, these
       methods can be applied to existing data to produce reliable counts of
       populations that are not easy to measure such as sofa surfers and
       households in concealed homelessness, improving area-based counts
       of homelessness groups.
       Finally, ad hoc models that identify treatment effects can be used to
       assess the effectiveness of previous or existing interventions. For
       example, a similar strategy was adopted to measure the impacts of
       realised changes in Local Housing Allowance (LHA) on a number of
       outcomes, including LHA entitlements, contractual rents and types of
       properties claimants live in. (Beatty et al., 2014). A difference-in-
       differences model was applied to administrative data on housing benefits
       claims from the Single Housing Benefit Extract (SHBE) to compare
       trends in outcomes (for example, rents and types of properties) for
       groups who moved into the new LHA system to groups with similar
       characteristics that have not rolled onto the new system yet.2

       Notes
       1
         For a more detailed discussion about capture-recapture methods see the “Review of models
       of homelessness” report.
       2
        For a comprehensive outline of the model developed to measure the impact of LHA reforms,
       see the report by Brewer et al. (2014).

                                                                                           Page 16 of 84
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2. Collections                                            population groups) to produce
                                                          granular short-term forecasts.

of data                                                   Previous collections of administrative
                                                          data on homelessness (collected using
                                                          P1E forms for people in temporary
                                                          accommodation), which are
2.1 Overview                                              aggregated at the local authority level,
                                                          included a limited set of background
There are three types of data which
                                                          information. The Homelessness Case
can be used to project homelessness
                                                          Level Information Classification (H-
and rough sleeping in the future and
                                                          CLIC) system for data collection which
evaluate the effects of policies aimed
                                                          will replaces the P1E forms, collects
at tackling homelessness and
                                                          household case level data providing
supporting people in need: 5
                                                          more detailed information on the
o administrative data on                                  causes and impacts of homelessness,
  homelessness and rough sleeping                         long-term outcomes for homeless
  collected by LAs and reported by                        households and what works best for
  MHCLG at frequent time intervals,                       preventing homelessness. Moreover,
                                                          administrative data on rough sleeping
o data at the household and/or                            collected using the Rough Sleeping
  individual level from large scale                       Evaluation Questionnaire (RSEQ)
  household surveys which include                         include information on individual socio-
  information on homelessness or                          economic characteristics that have
  surveys that were designed to                           been shown to be associated with
  explicitly cover homelessness and                       homelessness (e.g. financial strain,
  rough sleeping experiences, and                         use of other public services, mental
o administrative data (for example,                       health problems, etc.) Therefore,
  official statistics) on homelessness                    forthcoming collections of
  determinants – e.g. housing and                         administrative data can be used to
  unemployment benefits, housing                          estimate time series models that
  supply, private rents, demographic                      include limited sets of explanatory
  trends, health indicators, key                          variables in addition to historical values
  economic variables, etc.                                of the variables of interest (multivariate
                                                          models).
Time series models can be applied to
series of administrative data on                          H-CLIC and RSEQ data can be also
homelessness and rough sleeping that                      used to measure the effects of
are reported frequently (e.g. every                       predictive factors on different types of
quarter). These models can handle                         homelessness at the first stage of
large series of data inputs (for                          simulation models. Survey data and
example, across LAs and for particular                    other sources of statistics on key

55                                                         be found in the appendix.
 AAdetailed
    detailedoverview
             overviewof of existing
                        existing    data
                                 data    sources
                                      sources cancan be found in the appendix.

                                                                                       Page 17 of 84
Homelessness | Feasibility Study

determinants can also useful for                                   extrapolation of missing predictors
estimating homelessness projections                                using other observable characteristics)
using simulation models. Individual                                might lead to decreased output
data drawn from surveys can feed into                              accuracy. For instance, if data is not
components of simulation models to                                 available on a predictor that is highly
quantify behavioural responses to                                  correlated with homelessness such as
changes in important predictive                                    income, we would have to use an
factors. Detailed individual data from                             observable proxy such as socio-
surveys are necessary for developing                               economic status or educational
models that can produce granular                                   achievement to approximate individual
outputs – e.g. micro-simulation                                    income. We would then quantify the
components that produce                                            link from income to homelessness
distributional outcomes or generate                                based on this approximation, which
projections for subsamples with                                    would result in reliability losses in our
specific characteristics. Data on other                            homelessness estimates conditional
explanatory variables are also used in                             on income.
simulation models to arrive at
homelessness projections conditional                               In the case of homelessness and
on future trends in determinants.6                                 rough sleeping in England, existing
                                                                   sources of data on outcomes of
In principle, selecting suitable                                   interest and their determinants are
methodologies to project outcomes of                               adequate for applying models to
interest and evaluate policies does not                            predict future levels of homelessness
depend on data availability and quality                            under composite policy and economic
in the sense that there is no merit in                             scenarios. However, improving the
developing different methodologies for                             quality of existing data or collecting
different data. Analysts select the                                new detailed data on homelessness
methods they will use from a set of                                and rough sleeping will certainly
existing options and rely on available                             influence the model outputs – more
data to accommodate policy                                         detailed data lead to more reliable
objectives. When data is imperfect or                              outputs under the same empirical
not available, they make assumptions                               design.
to address the limitations imposed by
lack of data or data of low quality.
For example, when detailed data on                                 2.2 Evidence gaps
other life domains of homeless people                              and areas for
are not available, assumptions are
used to compensate for missing                                     improvement
knowledge about personal
                                                                   In this section, we highlight potential
characteristics that might influence
                                                                   areas for improvement in data
paths in and out of homelessness.
                                                                   collection based on gaps that we have
Such assumptions (including the

66                                                                 predictive factors.
     Seebox
     See boxA1
             A1ininthe
                    theappendix
                        appendixforforforecasts
                                        forecasts
                                                of of predictive factors.

                                                                                              Page 18 of 84
Homelessness | Feasibility Study

identified in existing data sources on                 contribution of broad policy areas to
homelessness and rough sleeping in                     reduction and preventions of
England. New collections of data and                   homelessness.
enhancements to already existing
systems for gathering information will                 Covering all homelessness types
result in more reliable estimates of
future trends in homelessness under                    The new Homelessness Reduction Act
alternative policy and economic                        2017 required local authorities (LA) to
scenarios. More detailed evidence of                   meet two new duties (relief and
homelessness experiences at the                        prevention) to all those affected,
individual level will contribute to a                  regardless of priority need or
better understanding of the causes                     intentionality.7
and impacts of homelessness as well                    Following this major change in policy,
as what works best for preventing and                  it is important that LAs gather
reducing homelessness.                                 information about types of
We also consider the importance of                     homelessness in addition to the former
suggested enhancements in data as                      definition of statutory homelessness –
part of developing a comprehensive                     for example, sofa surfing, squatting
evidence base that will result in more                 and living in hostels and other types of
reliable estimates of homelessness                     short-term or emergency
and rough sleeping. We categorise                      accommodation.
them in two groups:                                    The development of comprehensive
o top priority – data that are                         definitions of various homelessness
  necessary for generating robust                      types is central to the design of a
  projections of various                               systematic recording of homelessness
  homelessness types, and                              types that covers the entire range of
                                                       homelessness experiences in England
o further priority – data that can add                 – for instance, single people
  depth but are not central to                         homelessness, rough sleeping and
  achieving the aims of a suite of                     sofa surfing. A common and
  models around homelessness.                          comprehensive description of what
                                                       homelessness is and which groups of
                                                       people are owed support by public
2.2.1 Top priority                                     services in England will guide the
                                                       collection of consistent data on
In this section, we discuss                            homelessness outcomes of interest.
recommendations for improving data
on homelessness that are critical to                   Examples of collecting data on various
conducting a robust empirical analysis                 homelessness types are the additional
of homelessness trends, pathways in                    modules and questions included in the
and out of homelessness and the                        Rough Sleeping Questionnaire as well

 7
7 For a detailed discussion about the Act see here:    http://www.legislation.gov.uk/ukpga/2017/13/cont
 For a detailed discussion about the Act see here:
                                                       ents/enacted
http://www.legislation.gov.uk/ukpga/2017/13/contents/enacted

                                                                                        Page 19 of 84
Homelessness | Feasibility Study

as well as in the H-CLIC form for data                                 array of paths to the incidence of
collection. The Rough Sleeping                                         social problems such as
Questionnaire includes questions that                                  homelessness.
capture past experiences of sofa
surfing in addition to rough sleeping. It                              Poor linkage of data in the English
could be administered to all local                                     context is a major limitation to a
authorities in England and become                                      comprehensive analysis of
part of official statistics. Moreover,                                 homelessness that could contribute to
collecting data at regular time intervals                              a better understanding of the problem,
– for example, in annual or bi-annual                                  its causes at the personal, economic
waves – as well as adding a                                            and policy level and what policies are
longitudinal element to data collection                                needed to tackle it.
would improve statistics on rough                                      Administrative data covering a number
sleeping and contribute to a better                                    of areas including welfare benefits,
understanding of individual                                            health and use of public services can
experiences. The H-CLIC form is                                        be linked to other administrative data
completed by all local authorities and                                 on homelessness and rough sleeping.
includes a question about last settled                                 For example, the Single Housing
accommodation and type of                                              Benefit Extract (SHBE) dataset,
accommodation at the time of the                                       collected from LA records, is the key
application.8                                                          administrative source of monthly data
                                                                       on housing benefits claim. This
Data linking                                                           contains data on household type and
                                                                       demographic characteristics, amount
Using datasets that comprise linked                                    of monthly rent, share of the rent that
administrative data from distinct                                      is covered by Local Housing
sources that cover large numbers of                                    Allowance and type of
areas (e.g. benefits, health, institutional                            accommodation. Linking such benefit
history) is an important tool for                                      data to data on people who are either
research that aims to understand                                       homeless or at risk of homelessness
complex social issues and inform                                       would allow analysts to identify the
policy. It allows for capturing links                                  contribution of housing benefits to
between a broad set of predictors and                                  homelessness prevention.
outcomes of interest and mapping the

88  LAhomelessness
        homelessnessservices
                          services   applicants                         Service   accommodation;        no fixedatadobe;
   LA                             applicants     areare  asked about the
                                                      asked                type of    their accommodation           the time of the
                                                                        caravan/houseboat. In the cases where the
  application.
about    the typeThey  canaccommodation
                  of their  choose between:      at owner-occupier;
                                                    the time           shared ownership; private rented sector; council
                                                                        applicants report that their current accommodation
oftenant;  registeredThey
    the application.    provider  tenant; between:
                             can choose     Armed Forces accommodation; tied accommodation, looked after
                                                                        is not their last settled home, they are asked about
  children replacement;
owner-occupier;      sharedliving  with family;
                             ownership;     privateliving  with friends; social rented supported housing (or hostel);
                                                      rented
  refuge;council
           rough tenant;
                   sleeping;  homeless     on departure                 their accommodation         when   they were last settled in
sector;                    registered   provider    tenant; from institution
                                                                        order
                                                                               (custody/hospital);
                                                                                to capture    routes
                                                                                                       temporary
                                                                                                     into homelessness.        The
  accommodation;       student
Armed Forces accommodation; tiedaccommodation;          National  Asylum   Support     Service    accommodation;       no fixed
  adobe; caravan/houseboat.                                             applicants     can choose    between    owner/occupier;
accommodation,       looked after In   the cases
                                    children         where the applicants report that their current accommodation is not
                                               replacement;             shared ownership;
  their with
living  last family;
             settledliving
                      home,   they
                           with     are asked
                                friends;   socialabout
                                                    rentedtheir accommodation        when theyprivate
                                                                                                   were rented    sector;
                                                                                                         last settled       lodging
                                                                                                                        in order  to
  capture   routes  into homelessness.       The   applicants   can     (not with
                                                                     choose         family/friends);
                                                                              between                 council tenant;
                                                                                          owner/occupier;       shared   registered
                                                                                                                          ownership;
supported housing (or hostel); refuge; rough                            Provider   tenant;   living with  family tenant;
                                                                                                                 or friends;   looked
  private rented
sleeping;          sector;
            homeless        lodging (not
                        on departure    fromwith   family/friends); council
                                               institution                    tenant;   registered   Provider              living with
  family or friends; looked    after                                    after  children  placement;    social  rented
                                      children placement; social rented or supported housing; tied accommodation;       or   supported
(custody/hospital);    temporary   accommodation;                       housing; tied accommodation; Armed Forces
  Armed accommodation;
student    Forces accommodation.
                               National Asylum Support                  accommodation.

                                                                                                                Page 20 of 84
Homelessness | Feasibility Study

For example, the Public Health           o data on groups who are vulnerable
Outcomes Framework sets out                because of physical and mental
desirable health outcomes at the           health issues drawn by Mortality
national and subnational level and         Statistics, Mental Health Minimum
measures health indicators across LAs      dataset, Hospital Episode Statistics
in England. The dataset also includes      and the Health Improvement
two indicators on homelessness that        Network.
potentially allow for modelling links
between physical and mental health       There are various considerations
outcomes and homelessness at the         concerning issues related to technical
LA level. However, the indicators only   and legal aspects of the data linking
capture statutory homelessness at the    process. An important issue is
LA level, hindering the assessment of    anonymisation of data and security of
links between health outcomes and        information. Explicit guidelines and
other types of homelessness – such       protocols should be put in place to
as sofa surfing and rough sleeping.      ensure that it is not possible for
Given that mental health appears to be   analysts who use the dataset to link
a major determinant of rough sleeping,   data to people. For example, the
there is merit in expanding the          number of attributes included in the
accommodation response category in       compilation of administrative data is an
the Public Health Outcomes               issue to consider – a wide variety of
Framework to capture other types of      attributes could lead to the
homelessness and link the                identification of specific service users
observations to official statistics on   in small LAs, where limited numbers of
rough sleeping or administrative data    people experience homelessness.
collected using the Rough Sleeping       Despite the variety of issues that need
Questionnaire.                           to be considered, linking existing
Other sources of data that contain       sources of data could be a more
information on accommodation types,      straightforward and less costly – in
including homelessness, that could be    both resources and time – alternative
linked to homelessness data, such as     to expanding existing data sources or
H-CLIC, are the following:               designing new collections to capture
                                         additional information about people
o data on care leavers aged 17-21        who are either homeless or at high risk
  years old drawn by Children            of homelessness.
  Looked After in England,

o data on prisoners drawn by
  Accommodation Status of
  Prisoners and Police Records,

o data on groups of drug treatment
  services drawn by National Drug
  Treatment Monitoring System, and

                                                                   Page 21 of 84
Homelessness | Feasibility Study

       Box 3. Steps toward data linking in England: the Rough
       Sleeping Evaluation Questionnaire (RSEQ)

       The Rough Sleeping Evaluation Questionnaire (RSEQ) was introduced as part of
       the recent MHCLG initiative to tackle the most severe form of homelessness – i.e.
       rough sleeping. The new instrument for data collection contributes to existing
       approaches by collecting detailed data on individuals’ past and current
       experiences of rough sleeping and capturing a wider set of factors that are
       related to such experiences, including support needs, feelings and attitudes and
       health indicators.
       In addition to this contribution, the new method goes beyond prior approaches
       to data collection by proposing a scheme for data linking across administrative
       datasets. Personal details of service users interviewed with the RSEQ – such as
       names, date of birth, and national insurance number (if known) – are linked to:
       o administrative data on receipt of welfare benefits (DWP),
       o criminal justice system records (MoJ),
       o administrative data on statutory homelessness applications collected by LAs
         (MHCLG),
       o health care services use (NHS Digital),1 and
       o alcohol and drug treatment use (PHE).
       The output of this process is a comprehensive dataset that includes detailed
       information about a broad set of areas – history of rough sleeping, statutory
       homelessness applications, support needs, contact with the criminal justice
       system, receipt of welfare benefits, healthcare use and participation in substance
       use treatment – but excludes service users’ personal details.
       Assembling such detailed lists of administrative data for users of homelessness
       prevention and treatment services is important for understanding the needs of
       people who sleep rough or are homeless and assessing wider costs of
       homelessness that potentially exceed the costs of delivery of homelessness
       services alone.

       Notes
       1
        Linking RSEQ data to information on public health service use is likely to be
       challenging. Evidence from the Homelessness Link survey on the health
       outcomes of homeless people shows that while 90% of the 2,500 surveyed
       homeless and rough sleeping individuals are registered with a GP, the rough
       sleeping groups use GP services the least. See here for more information:
       https://www.homeless.org.uk/sites/default/files/site-
       attachments/The%20unhealthy%20state%20of%20homelessness%20FINAL.pdf

                                                                                Page 22 of 84
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       Data from people in households that have been assessed as homeless
       by Scottish local authorities (LAs) were linked to a number of health
       datasets covering the following areas: accident and emergency
       attendance; alcohol-related admissions; drug misuse-related
       admissions; emergency admissions related to injury and poisoning;
       psychiatric admissions; and non-attendance at outpatient appointments.
       LAs in Scotland do not normally reveal personal information of applicants
       when sharing data with government departments. For the purpose of
       this project, all LAs were asked to submit personal identifiable
       information for people who were considered homeless or at risk of
       homelessness to the National Records of Scotland (NRS) Indexing
       Service.
       A dataset including personal information about the applicants – such as
       homelessness application number, name, gender, date of birth,
       postcode and local authority code – was created particularly for the
       purpose of data linking. Using the application numbers, this new dataset
       could be linked back to the homelessness datasets assembled by
       Scottish LAs.
       In order to match homelessness with health data, a ‘separation of
       function’ approach was adopted to ensure that no single organisation or
       individual had access to the entire range of datasets required for this
       project. A third party (the NRS Indexing Service) matched the
       homelessness dataset that was created for the purpose of this project
       with the Research Indexing Spine (RIS) – a population compiled by NRS
       that uses information drawn from general practitioner (GP) registries at a
       single point in time (snapshot). The NRS Indexing Service performed the
       matching only using personal identifiers across the datasets – access to
       the rest of the data was restricted. Each matched individual was then
       assigned the Community Health Index (CHI) number that tracks
       individual usage of health care services.
       When matching was completed, the matched results were combined
       with the rest of the data and the personal identifiers were removed.
       Analysts accessed this secondary dataset in a separate and secure
       environment.

                                                                          Page 23 of 84
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       Box 4. Best practices in data linkage: the Scottish
       example

       The Scottish government has recently adopted a strategy to promote
       better use of existing administrative data to understand important social
       and economic issues and evaluate policies.
       Data linking is central to this new approach, which draws on a thorough
       Data Linkage Framework established in 2012 to promote collaboration
       and best-practice sharing among key public sector organisations that
       collect and handle registry data.
       A set of guiding principles has been developed to “support the legal,
       ethical and efficient use of data for linkage purposes within a controlled
       and secure environment”.1 The principles set out important priorities
       and considerations related to acting in the public interest, transparency,
       privacy (consent, anonymisation and security of individual data), data
       access and consequences when these principles are disregarded.
       Efforts have been made to ensure that linked administrative data are
       anonymised and secure, personal information is protected, and
       individuals cannot be identified in the datasets. Several anonymisation
       methods are applied, including complete anonymisation, which
       excludes all identifiers of personal information from the datasets, and
       pseudonymisation, where identifying fields (such as names) are
       replaced with artificial identifiers (such as unique serial numbers).
       Moreover, safe havens were launched as a way to ensure privacy –
       these are secure environments where researchers have access only to
       the anonymised segments of secondary datasets relevant to their
       research.

       Homelessness data linking
       One example relevant to analysing homelessness is linking data on
       homelessness to national-level health datasets. Homelessness data
       were linked with individual health indicators in order to quantify the use
       of health services by homeless groups in Scotland (Waugh et al., 2018).

       Notes
       1
        For more information about guiding principles for data linkage in Scotland see here:
       https://www.gov.scot/Topics/Statistics/datalinkageframework/GuidingPrinciples

                                                                                       Page 24 of 84
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