Hello,
I have a binary variable (yes/no) and two measuring time (T1 and T2). Thus data are not independant.
I would like to calculate the difference (in percentage) between the proportion of "yes" at T1 and the proportion of "yes" at T2. Moreover i need to calculate the confidence interval of this difference.
I thought it was possible using proc freq (as paired ttest) but i wasn't successufll at getting it to work.
Hoping that you can help me.
Thank you.
Thanks a lot for your response.
Later readers of this thread should note:
The blog article linked in the accepted solution is about proportions in independent samples. The confidence intervals for a proportion difference in that situation will tend to be too narrow when applied to dependent (paired) samples.
A discussion of CIs for the latter situation (including SAS code) can be found in the SESUG 2013 paper SAS® Macros CORR_P and TANGO: Interval Estimation for the Difference between Correlated Proportions ....
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