H571 Week 3 - Carpenter-HBM - Natalie
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Transcript H571 Week 3 - Carpenter-HBM - Natalie
“A meta-analysis of the
effectiveness of health
belief model variables in
predicting behavior”
Carpenter, 2010
Natalie Linton
Oregon State University
October 9, 2014
What is the Health Beliefs Model (HBM)?
Developed by the U.S.
Public Health Service in the
1950s
Based in value-expectancy
theory
measles
http://xkcd.com/51/
What is a meta-analysis?
Statistical methods for
contrasting and combining
results from different studies
Meta-analyses can identify:
patterns
sources of disagreement
Previous HBM meta-analyses:
Janz & Becker 1984
barriers, benefits, susceptibility
did not estimate mean effect sizes
Harrison et. al. 1992
retrospective studies = larger effect
sizes than prospective
did not correct effect size estimates
Zimmerman & Vernberg 1994
HBM prediction weak compared to
Social Cognitive Theory and TRA
did not examine the effects of each
variable on behavior
Why did Carpenter conduct
a meta-analysis of the HBM?
Determine whether measures of HBM
concepts could longitudinally predict
behavior
Which elements are strong predictors?
What are the moderators?
Moderators found:
Time between variable measurement (Time 1)
and outcome behavior measurement (Time 2)
Type of outcome behavior:
Prevention or treatment
Drug-taking or not drug-related
Methodology
18 studies (2,702 subjects); published 1982-2007
Looked at only the first 4 concepts of HBM:
Susceptibility (18), severity (17), barriers (17), benefits (15)
Studies had to include at least 2 of the 4
Studies had to be longitudinal
Time 1: measure HBM variables
Time 2: measure health-related behavior outcome
Outcome dichotomized as treatment (8 studies) or prevention
behavior (10 studies)
Outcome also dichotomized as drug-taking behavior (5
studies) or other behavior (13 studies)
Results
Results
Perceived susceptibility
Usually not correlated with health behavior (weakest
predictor)
Estimates mostly homogenous
Subset of drug-taking studies only set for which
susceptibility was positively correlated with behavior
Moderator: length of time
Longer periods of time between Time 1 and Time 2
associated with weaker effects
r = -0.50
Perceived severity
“There is something about about considering complying
with a prescription to take drugs that causes people to
consider the severity of the consequences for not
taking the drugs more so than for other health
behaviors”
Moderator: length of time
Severity ratings more likely to be positively correlated to
behavior if the behavior is measured shortly after Time 1
r = -0.37
Perceived benefits and barriers
Strongest predictors of
behaviors
Stronger when dealing with
preventive behavior
Findings mostly consistent
with previous literature
Moderator for perceived
benefits: length of time
Longer periods of time
between Time 1 and Time 2
associated with weaker effects
r = -0.59
http://xkcd.com/388/
Limitations
Small number of studies
Not enough articles providing effect sizes
Variety and varying quality of measures used
16 (of 18) articles relied on convenience samples
Did not test more complex models that are possible
and would be better to test (studies would have needed
to report full correlation matrices)
Levels of
Causation
Intrapersonal Stream
Biological/Nature
BIOLOGY/
PERSONALITY
Ultimate
Causes
1
Social/
Personal
Nexus
2
Sense of
Self/Control
Distal
Influences
7
13
8
h
Skills:
Social+General
14
Proximal
Predictors
b
c
B
C
Others’
Beh & Atts
9
i
k
j
l m
u
d
e
n
16
SOCIAL
NORMATIVE
BELIEFS
o
11
w
20
q
Values/
Evaluations
x
v
6
Interactions w/
Social Instit’s
p
Perceived
Norms
15
5
f
10
Motivation
to Comply
s
CULTURAL
ENVIRONMENT
4
Interpersonal
Bonding
19
A
Nurture/Cultural
3
SELF-EFFICACY t
BEHAVIORAL
CONTROL
Affect and
Cognitions
Cultural/Attitudinal Stream
SOCIAL
SITUATION
a
Social
Competence
g
Self
Determination
Expectancies
& Evaluations
Decisions
Social/Normative Stream
Information/
Opportunities
Knowledge/
Expectancies
17
F
21
I
22
Trial Behavior
EXPERIENCES: Expectancies -- Social Reinforcements -- Psychological/Physiological
Experiences
18
ATTITUDES
TOWARD THE
BEHAVIOR
DECISIONS/INTENTIONS
D E
12
r
23
J
K
Related Behaviors
H
G
Discussion
Why do you think Carpenter found perceived
susceptibility to have almost no relationship to health
behavior?
Why do you think time between measures worked as a
moderator for susceptibility, severity, and benefits?
Why was time between measurements not a moderator
for barriers?
References
Christopher J. Carpenter (2010): A Meta-Analysis of the
Effectiveness of Health Belief Model Variables in Predicting
Behavior, Health Communication, 25:8, 661-669.
DiClemente, R.J., Salazar, L.F., & Crosby, R.A. (2013). Health
Behavior Theory for Public Health: Principles, Foundations and
Applications. Jones and Bartlett, Boston, MA.
TTI slides provided to H 571 class at Oregon State University.