How to cra the "Approach" sec1on of an R grant applica1on
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How
to
cra)
the
“Approach”
sec1on
of
an
R
grant
applica1on
David
Elashoff,
PhD
Professor
of
Medicine
and
Biosta7s7cs
Director,
Department
of
Medicine
Sta7s7cs
Core
Leader,
CTSI
Biosta7s7cs
Program
Overview • Preliminary Data • Study Design • Sample Size and Power Analysis • Sta7s7cal Methods • Collaborators • Wri7ng Strategies
Preliminary
Data
• Primary
Ques7on:
“Is
there
reason
to
believe
that
the
study
hypotheses
could
be
true
and
is
this
research
team
capable
of
carrying
out
the
study?”
Necessary
Elements:
Preliminary
Data
• Strong
and
relevant
preliminary
data
key
for
R01
grants
• Demonstrate:
– Exper7se
with
assays
– Novel
assays
work
in
pa7ents/samples
to
be
collected
– Support
for
hypotheses
• Use
figures
and
tables
where
possible
Ways
to
Fail:
Preliminary
Data
• Insufficient
annota7on
for
figures/tables
• Poor
data
analy7c
techniques
• Weak
support
for
hypotheses
• Unrealis7cally
strong/naïve
preliminary
results
• Presen7ng
needle
in
a
haystack
results
• Presen7ng
too
much
preliminary
data
at
expense
of
rest
of
the
approach
Study Design • Primary Ques7on: “Is the design of the study appropriate to address the study aims?”
Necessary Elements: Study Design • What is overall study design (RCT, Cohort study, Case-‐Control, Cross-‐sec7onal, Biomarkers) • Describe endpoints and clarify, if necessary, how they will be quan7fied and their measurement scale. • Describe study popula7on and control groups • Inclusion/Exclusion Criteria • Describe all study measures with appropriate measurement process details
Addi7onal
Considera7ons:
Study
Design
• Describe
exis7ng
popula7on
clearly.
-‐
Include
relevant
demographics
-‐
Include
informa7on
on
prognos7c
or
confounding
measures.
• Nothing
says
that
this
is
a
ready
to
go
study
be^er
than
a
clearly
defined
popula7on
that
is
relevant
to
the
study
aims.
Addi7onal
Considera7ons
• Randomiza7on
methods
for
clinical
trials
• Collect
confounding
factors
• How
long
will
follow-‐up
period
be?
• Validity
and
reliability
of
study
measures
• Subject
matching?
• Valida7on
of
model
building
either
with
cross-‐
valida7on
or
training-‐test
designs
Ways to Fail: Study Design • Study popula7on or design doesn’t match objec7ves • Insufficient 7me for recruitment and follow-‐ up. • Lack of clarity with respect to availability of subjects • Very uninteres7ng to read technical details of assays that are standard
Sample Size • Primary Ques7on: “Is the sample size sufficient to give the study the ability to answer the primary study ques7ons?”
Necessary
Elements:
Sample
Size
• Iden7fy
study
endpoint(s)
for
all
aims.
• Clearly
describe
sample
size
for
each
aim
• For
each
endpoint:
– What
is
the
effect
of
interven7on
or
magnitude
of
the
rela7onship?
– How
much
variability?
– Level
of
power?
– One
or
two
sided
test?
– What
is
the
sta7s7cal
test
used
to
compute
power?
Addi7onal Considera7ons: Sample Size • Account for study dropouts • Account for mul7ple comparisons (either Bonferroni or False Discovery Rate) • Ocen useful to examine sample sizes for a variety of scenarios when uncertainty exists concerning what is to be expected for an endpoint
Ways to Fail: Sample Size • No power analysis • Sample size calcula7on does not have sufficient informa7on for a reviewer to replicate • Sample size calcula7on does not use relevant preliminary data or methods described in the sta7s7cal analysis sec7on. • Predic7on modeling with large number of predictors rela7ve to sample size • Unrealis7c assump7ons about magnitude of effect
Bad Examples “A previous study in this area recruited 150 subjects and found highly significant results (p=0.014), and therefore a similar sample size should be sufficient here.” “Our lab usually uses 10 mice per group.” “Sample sizes are not provided because there is no prior informa7on on which to base them.” "The throughput of the clinic is around 50 pa7ents a year, of whom 10% may refuse to take part in the study. Therefore over the 2 years of the study, the sample size will be 90 pa7ents. “ “It is es7mated that for a sample size consis7ng of 6 animals in each trial and with a tumor volume variance from 0.1 to 1.0 cm3 – that when the difference in the popula7on reaches 0.25, the power will reach 100%.”
Good Examples “A sample size of 38 in each group will be sufficient to detect a difference of 5 points on the Beck scale of suicidal idea7on, assuming a standard devia7on of 7.7 points, a power of 80%, assuming a two sided significance level of 5% and a two sample t-‐test. This number has been increased to 60 per group (total of 120), to allow for a predicted drop-‐out from treatment of around one third. This difference of 5 points is based on our prior study in which….. ” “A sample size of 292 babies (146 in each of the treatment and placebo groups) will be sufficient to detect a difference of 16% between groups in the sepsis rate at 14 days, with 80% power. This 16% difference represents the difference between a 50% sepsis rate in the placebo group and a 34% rate in the treatment group. This assumes a Chi-‐ square test with a two sided 0.05 significance level. This es7mated difference in sepsis rate is based on the study of Bob et al [ref] in which they observed….”
Sta7s7cal Methods • Primary Ques7on: “Are the sta7s7cal methods appropriate for the analysis of the data that will be collected?”
Necessary
Elements:
Sta7s7cal
Methods
• Need
methods
sec7on
for
each
aim.
• Clearly
describe
analy7c
strategies
for
each
endpoint.
• Methods
should
be
appropriate
for
type
of
variable
(ex.
categorical,
ordinal,
count)
and
study
design
• Typically
includes
inferen7al
tes7ng
of
endpoints
and
model
building
Addi7onal
Considera7ons:
Sta7s7cal
Methods
• Sta7s7cal
methods
appropriate
for
sample
size
(ex.
Fisher
test
vs
Chi-‐square
test)
• Include
evalua7on
and
valida7on
strategies
for
regression/predic7on
models
• Can
include
model
assump7on
checking
methods
• Accoun7ng
for
missing
data
Ways to Fail: Sta7s7cal Methods • Ignoring key confounders or demographic variables. • Ignoring standard prognos7c or predic7ve measures in models • Describing socware but not ideas/methods • Analy7cal approach not appropriate for design and research ques7on
Ways to Fail: Sta7s7cal Methods • Ignoring key confounders or demographic variables. • Ignoring standard prognos7c or predic7ve measures in models • Describing socware but not ideas/methods • Analy7cal approach not appropriate for design and research ques7on
Collaborators • Primary Ques7on: “Does the study have appropriate collaborators with sufficient effort to perform the research described?”
Necessary
Elements:
Collaborators
• Need
an
iden7fied
sta7s7cal
collaborator
with
appropriate
experience
• Biosketchs
for
faculty
collaborator
• Budget
jus7fica7on
for
collaborator
• Le^er
of
Support
if
no
funding
is
in
applica7on.
– Make
use
of
collaborators
from
on-‐campus
service
groups.
(Ex:
CTSI,
Cancer
Center)
Addi7onal
Considera7ons:
Collaborators
• Staff
collaborator
only
need
biosketch
if
no
faculty
on
applica7on.
• Can
include
small
%
effort
for
expensive
faculty
and
larger
%
for
staff
support.
• Make
sure
areas
of
weakness
are
covered
with
experienced
collaborator
• Don’t
include
many
collaborators
with
minimal
effort
• Not
enough
to
men7on
collaborators
and
write
that
they
will
take
care
of
details
Wri7ng
Strategies
• Use
the
resources
and
human
subjects
sec7ons
to
full
effect
– Can
give
details
of
available
study
popula7on
and
subject
demographics
• Standard
experimental
methods
can
be
referenced
• Long
blocks
of
text
are
boring
a
can
ocen
get
skimmed.
• Emphasize
key
points:
bold,
underline
Wri7ng Strategies • Graphical displays: – Theore7cal Framework – Experimental Design – Aims flowchart – Pa7ent characteris7cs – Study measures
Don’t Waste Space
Grant
Applica7ons
Assistance
• Assistance
with
preparing
grant
applica7ons
(CTSI)
– Study
Design
– Data
Analysis
Protocols
– Sample
Size
and
Power
Analysis
– Budge7ng
and
Iden7fying
Appropriate
Collaborators
– Core
facili7es
• Substan7al
lead
7me
with
opportunity
for
mul7ple
itera7ons
is
necessary
for
high
quality
grant
applica7on
assistance:
Study
Design
vs
Analysis
sec7ons
Final Thoughts • Consult sta7s7cal collaborator for study design and approximate sample size some weeks in advance • Most successful proposals require mul7ple itera7ons of research design sec7ons
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