st: Wilcoxon signed-rank test for clustered data

["Harsha" <harshabl.76@gmail.com>]

Dear All,

I have a data comparing a few parameters in a group of patients before and
after a particular surgery. These surgeries are done on both eyes of a few
patients resulting in a correlated data. A few variables which I am trying
to compare are non-parametric. I am trying to apply Wilcoxon signed rank
test but am faced with the problem of the observations being not independent
between the 2 eyes of the patients. There is a program on SAS by Rosner's
group to use Wilcoxon for clustered data. Is there something similar in
stata? Is there any other ways to compare the medians between groups in
correlated data?

Kindly suggest.

Harsha

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