Re: Selecting a Statistical Test for unmatched pre post survey

Posted by Bruce Weaver on Sep 22, 2011; 7:02pm
URL: http://spssx-discussion.165.s1.nabble.com/Selecting-a-Statistical-Test-for-unmatched-pre-post-survey-tp4830008p4831188.html

When I responded earlier, I understood you to have two completely different (independent) groups of students pre and post program.  Things are clearer now.  But it's still not clear to me whether you can match for those students with two data points.  If you cannot match, then I would do as others have suggested and use an independent groups t-test.  

If you can match for students with two data points, you could use a multilevel model with occasion clustered in ID (using the MIXED procedure).  In that kind of model, it's fine for some students to have only 1 of the two data points.  Note that this would require a data set with one row per data point rather than one row per student (with a variable indicating pre vs post).  

HTH.

seguchi wrote

Most of the pretest cases are the same as the posttest cases. However, some students dropped out of the program, so they took only pretest not posttest. And some students jumped into the program (due to change of school or...), and took only posttest no pretest. There were a lot of errors when administering the the survey/the pre test.