Dear Stata users,
This is a basic stat question. In an intervention
trial to increase seat belt use 328 adults were
randomized to either a no intervention group(control)
or an educational intervention. After a few months
they were contacted and asked questions about their
seat belt use. Here is the resulting data:
Pecent seat belt use:
intervention before after
Yes 29% 58%
No 40% 52%
The randomization was such that the baseline for the
two groups was NOT the same. How can I correctly test
if the intervention worked given that the baselines
are different and there is a ceiling effect (i.e.
percents can not exceed 100%).
Thank you very much,
Ricardo.
=====
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK
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