Download PEDS 409 Research Design: True Experimental

PEDS 409 Research Design:
True Experimental
BY: Sherri Beauchamp, Marie
Buchta, Avaleigh Wagner & Jodi
Spink
Li, F. et al. (2001) Tai Chi
Enhances Self-Efficacy and
Exercise Behavior in Older
Adults. Journal of Aging
and Physical Activity (9):
161-171.
Authors and Affiliations
Fuzhong Li: Oregon Research Institute
Edward McAuley
Peter Harmer
Terry E. Duncan
Nigel R. Chaumeton
Grants from: National Institute on Drug
Abuse and National Institute on Aging
Research Question
What are the effects of a Tai Chi
intervention program on perceptions of
personal efficacy and exercise behavior
in older adults?
Type of Research
True Experimental
One or more control groups AND one or more
treatment groups
Random assignment from population of interest
Variables of interest can be manipulated directly
Type of Research (con’t)
Randomized Control Trial Design
R
R
O1
O1
X1
O2
O2
X2
R = Randomized Samples
O1-3 = Observations
X1-2 = Tai Chi intervention
O3
O3
Type of Research (con’t)
Advantages
Good for assessing change during and after
intervention
Main threats are controlled (testing, maturation etc.)
Disadvantages
Attrition rates
Diffusion of intervention (ie control group increases
activity)
Resentment for no intervention
Research Methods
Individuals responded to newspaper ads
and flyers at senior centers
Inclusion criteria
 65 years of age or older
Low active according to PASE (Physical Activity
Scale for the Elderly)– no involvement in regular
exercise program within the last month
Healthy – exercise will not have negative physical
effects
Willingness to be randomly assigned
Research Methods (con’t)
98 individuals 65-96 years old were
chosen
Assigned to either a Tai Chi practice
group or a waiting list
Assessed demographic characteristics:
age, gender, education, income &
ethnicity
6 month trial
Research Methods (con’t)
Intervention group
Yang Style Tai
Chi
60 min. practice
sessions 2x/week
for 6 months
15 min. warm
up, 15 min cool
down included in
practice session
Control Group
Maintained
routine activities
Could not join
new exercise
programs
Promised a 4
week Tai Chi
program at the
end
What is Yang Style Tai Chi?
Yang Style Tai Chi is a slow moving form that affects balance
postural alignment & concentration
Research Methods (con’t):
Outcome Measures
 Barrier scale selfefficacy
5 items to assess
perception of ability
to perform Tai Chi
regularly in the face
of barriers (ie. Pain,
boredom etc.)
0-100 confidence
scale (0=very little
confidence,
100=complete
confidence)
 Performance scale selfefficacy
3 item task-specific,
time-based
Degree of confidence
in ability to
successfully perform
a series of slow,
rhythmically
changing body
position movements
0-100 confidence
scale
Outcome Measures con’t
Class Attendance
Exercise behavior was assessed by
attendance taken by instructor
Frequency of Measurements
Baseline measures - prior to study
2nd measures – week 12
3rd measures – week 24
(intervention group responded in class within 1
week, control group responded by mail)
Main Findings
Tai Chi exercise program can
significantly enhance perceptions of taskspecific personal efficacy in older adults
The Tai Chi group developed higher
perceptions of efficacy, adhered better to
the exercise program and spent more time
engaged in exercise (therefore increased
exercise participation)
Main Findings (con’t)
Intervention (Tai Chi) group
Both types of efficacy increase over time
Initial boost from baseline to 2nd observation
Maintenance from 2nd to 3rd observation
Class attendance was significantly predicted by the
changes in the 2 types of efficacy
Control group
Both types of efficacy decreased over time
Main Findings (con’t)
Change in barrier
efficacy between Tai
Chi and Control
Change in
performance efficacy
between Tai Chi and
Control
Brief Critique
All subjects were volunteers – this could make
generalizability difficult
Gender was recorded but not specified in
results – potential influence of a moderator
variable
Monitoring attendance issues – no parameters
set aside for absenteeism - assumption that
absenteeism is due to self-efficacy
All self-efficacy measures are self-reported
therefore subject to social desirability biases
Brief Critique (con’t)
Physical activity in control group was not
monitored throughout the study
No data comparing the decrease in self-efficacy to a
decrease in activity
Motivation issue – feel obligated to attend
because are in the study
Would participants attend these classes if not in the
study? (long term adherence)
Validity of claim: intervention should be
compared to other organized activities/classes
Brief Critique (con’t)
Ethical issues: Control group was only offered
a 4 week Tai Chi class after the study, whereas
intervention group got 6 months
Self-efficacy measures are based on
performance of Tai Chi not general daily
activity (not applicable to control group)
Warm up and Cool down not specified
Sample size decreased due to attrition which
could impact generalizability
Future Research Suggestions
Compare Tai Chi results to more
Traditional forms of exercise (ie. Strength
training, walking, stretching, etc.).
Compare positive effects of Tai Chi in
other age groups.
Look at adherence over longer periods of
time or post-intervention (months, years
later)
Future Research Suggestions
(con’t)
Impact of Tai Chi on health & related
aging problems as compared to other
activities/interventions.
Examine impact of Tai Chi on adherence
to/participation in activities of daily
living
Other questions that can be
addressed with True
Experimental Research
Can be used for any study involving an
intervention (ie. Drug, exercise,
acupuncture, rehabilitation therapy, any
lifestyle factor etc.) on a sample of a
specific population
THE END