Comparing proportions with 'some' dependencies

Posted by Charlotte-9 on Apr 03, 2007; 12:13pm
URL: http://spssx-discussion.165.s1.nabble.com/Comparing-proportions-with-some-dependencies-tp1074868.html

Dear all,

Just something I've been pondering and would like your thoughts on.  If I
need to compare two proportions and the associated groups contain 'some'
of the same people but also some different people, can I simply assume
independence and use a Chi-squared test, or do I need to somehow take the
dependencies into account with, say, McNemar's test?

For instance, let's say we have two distinct rounds of a medical exam and
32.5% complete the exam in the first round whereas 28.6% complete the exam
in the second round.  Some people will have undertaken the exam in both
rounds whereas some people will be new to each round.  I want to state
whether there has been a significant decrease in uptake.

Thanks for your help,

Lou