http://spssx-discussion.165.s1.nabble.com/Pretest-to-Posttest-A-question-of-reliability-tp5717078.html
Dear Everyone,
We do a pretest-posttest analysis for a unidimentional scale with 10 items (say, Q1, Q2, ...,Q10). Using the pretest data, only four items (Q2, Q3, Q4, Q5) were significant, while using the posttest data six items(Q1, Q2, Q6, Q8, Q9, Q10) were significant. Noticed that the scale has a different set of items in the pretest and posttest scenario. Our question is, is the scale not reliable?
Suppose we extend the scenario above to more than two measures
(say, Pretest, Posttest1, Posttest2, Posttest3, Postest4) so that we will use the Latent Growth Modeling(LGM) to model the latent change. Is it a requirement in LGM that all the scale indicators/items are significant across tests?
Thank you for your inputs.
Eins