This might be a fairly elementary query....
I'm trying to use the SAMPSI function to help me
design a survey which will compare baseline and
follow-up observations in case and control
communities.
The STATA help file for SAMPSI explains how to use the
function to compare case and control observations in a
cross-sectional survey design (ie with one time
point), for either a comparison of means or a
comparison of proportions. When using it to design a
comparison of proportions, SAMPSI of course doesn't
ask for the estimated standard deviation of the
variable being observed.
The help function also explains how to use SAMPSI to
conduct a comparison of means where there is more than
one observation over time.
However, there's a gap - no apparent way of
calculating the sample size for a two-group comparison
of PROPORTIONS where there are repeated observations
in time.
Can anyone suggest anything?
Thanks.
MG
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