Date:         Fri, 21 Feb 1997 01:13:32 GMT
Reply-To:     tanks@UNIXG.UBC.CA
Sender:       "SPSSX(r) Discussion" <SPSSX-L@UGA.CC.UGA.EDU>
From:         tanks@UNIXG.UBC.CA
Organization: University of British Columbia, Vancouver, B.C., Canada
Subject:      mean substitutions

Hi all,
Is there a simple way to get spss to substitute means over a set of items
with different numbers of items in each subscore? I have several tests to
obtain an alpha coeffecient in which for the same test some participants
filled in 5 questionnaires and others four.  I am familiar with the standard
format of (test1+test2+test3)/(possible tests-testsdone)*(possible # tests).
Does spss
7.0 have a quick way of mean substituting missing data eg if person 1 did
all 4 tests and got a score, then person 2 did 5 tests, I want to compare
over the maximum possible tests which would mean a mean sub for the
person who did 4 tests and what their score would be averaged over 5
possible tests. The idea is that we want to calculate reliabilties based
on the same number of tests and some people are short one so I was
thinking of adding the mean over the first 4 tests as the score for test 5.
Thanks,
Lisa