Posted by
Poes, Matthew Joseph on
Aug 14, 2012; 4:21pm
URL: http://spssx-discussion.165.s1.nabble.com/Analyses-Confused-tp5714671p5714691.html
An RMANOVA will actually have to be an RMANCOVA, but with only 2 data points, will effectively only be an ANCOVA. What you want is an ANCOVA. RMANOVA can only be used with 3 or more data points. SPSS will let you do it, but it's not an RMANOVA, its an ANOVA then. Treatment/Control is based on a dummy variable, and the covariate should be the pre-test (as I indicated). You could create a pre-post variable, and a treatment-control variable, and stack the data (each person has two records then), but the former approach I mentioned is accepted as a superior approach. The reason is because it allows you to associate that variable with the individual. The latter approach is literally comparing it as if it were 4 separate groups, when in fact, its only 2 groups and 2 time points.
Matthew J Poes
Research Data Specialist
Center for Prevention Research and Development
University of Illinois
510 Devonshire Dr.
Champaign, IL 61820
Phone: 217-265-4576
email:
[hidden email]
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]] On Behalf Of StatsUser
Sent: Tuesday, August 14, 2012 11:09 AM
To:
[hidden email]
Subject: Re: Analyses - Confused
Thank you, those are useful points.
My confusion lies in the fact that yes I can do a paired t test, but must do a split file on the IV (information 2 levels - control, experimental) each have a pre post test on trust, in order to determine if there are significant differences on pre post trust measure in the experimental group alone (and control group alone). Does it makes sense to do a series of paired t tests, split filed on the IV?
Also, I am not only interested in the difference within each group (experimental and control pre post trust measure) but also across the groups (sig diff between experimental and control).
Hence, I am leaning toward RMANOVA, but would like to get other perspectives/rationales.
--
View this message in context:
http://spssx-discussion.1045642.n5.nabble.com/Analyses-Confused-tp5714671p5714688.htmlSent from the SPSSX Discussion mailing list archive at Nabble.com.
=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD