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Date:         Wed, 7 Sep 2005 19:37:22 +0100
Reply-To:     starborn@statisticsdoc.com
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Keith Starborn <starborn@statisticsdoc.com>
Subject:      Re: Test - Retest
Comments: To: "Franson, Jessica Leigh" <fransonj@UWEC.EDU>
In-Reply-To:  <B14120EE5C432443B21102F7925DAD020266B31F@COKE.uwec.edu>
Content-Type: text/plain; charset=ISO-8859-1; format="flowed"

Keith Starborn www.statisticsdoc.com

Dear Jessica,

A few suggestions - before conducting a test-retest analysis of the stability of the scores over time, it would be good to first establish at least the following conditions:

1. At each time point, the scales have high internal consistency,

2. At each time point, the scales have a similar dimensional structure (the suggestion to use SEM to look at the invariance of factor structure is an excellent one),

3. There is reason to believe, theoretically, that the scores should be relatively stable over time. What is being measured? Some constructs are changeable for good reason. Who is being surveyed? Some subjects may be exposed to conditions that are intended to differentially change scores on the construct.

To the extent that these conditions are met, an analysis of the correlation between scores over time is more likely to be meaningful.

HTH,

KS

Quoting "Franson, Jessica Leigh" <fransonj@UWEC.EDU>:

> I'm working with someone who recently conducted some survey research. > He surveyed the same group of people twice over a certain period of time > and wants to test the validity of the results by comparing both data > sets. What's the best way to go about this? > > Thanks, > Jessica Franson > > > Jessica Franson > Note: New email is fransonj@uwec.edu <mailto:fransonj@uwec.edu> > Instructional Technologist/Statistical Software Consultant > Network for Excellence in Teaching > Learning &Technology Services > University of Wisconsin-Eau Claire > (p) 715.836.4734 > (f) 715.836.6001 > http://www.uwec.edu/net <http://www.uwec.edu/net> > > >

-- For personalized and experienced statistical consulting, visit www.statisticsdoc.com


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