(Others) Credibility established. But, wasn't this a more complex homework problem than would be expected on first or second week of the semester?
To add to what Bruce posted.
If the TX*PET term (PET = pre-existing trait) is significant, you'll need to look at a moderation analysis, which has an established literature (and a downloadable spss macro). One key name is Kristopher Preacher (quantpsy.org); another is Andrew Hayes.
Gene Maguin
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]] On Behalf Of James Ross
Sent: Wednesday, September 07, 2016 5:13 PM
To:
[hidden email]Subject: Re: ANCOVA SPSS Question HELP
I should give more info since I believe my first message was interpreted as someone who is doing homework for a college or high school class. Here are the specifics of what I need help with:
I gathered data on 1000+ participants and measured their attitudes via a standardized measure that uses Likert scale responses. This measure which I'll call my attitude measure was given before and after an intervention.
There were three groups for the intervention. Participants were randomly assigned to Intervention Group A, Intervention Group B, and a control group. The control group was not given any intervention but did a random task. All three groups completed the Pre-Test and Posttest attitude measure. I am hypothesizing that Groups A's intervention post-test scores will be less than Group B's intervention post-test scores and that both A and B group's post-test scores will be less than the control group's post-test score.
In addition, before administering my attitude measure, I administered a scale that is meant to measure a specific pre-existing trait. This measure also uses Likert scale responses and produces an ordinal sum total ranging from 10 to 50. I'm calling this my moderating variable because I believe that the Pre and Post test scores will decrease even more for those that have a higher score on my trait measure. But I don't understand how to put all these scores in SPSS.
Someone earlier said that this was not an ANCOVA, but I thought any pre-post test comparisons with group assignments had to have the Pre-test scores put down as a Covariate? Plus I don't know where to put (what I believe is moderating) my trait measure score? Conceptually, isn't it also a covariate or is it something else?
I hope this clears up earlier message.
Thanks,
James
=====================
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