Date:         Wed, 15 Sep 2010 10:03:06 -0400
Reply-To:     R B <ryan.andrew.black@gmail.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         R B <ryan.andrew.black@gmail.com>
Subject:      Re: Chow test to compare regression on two groups
In-Reply-To:  <1284496193815-2839766.post@n5.nabble.com>
Content-Type: multipart/alternative;

Jose,

You've clearly sparked a lot of interest from several people, and my guess
is, you'll continue receive useful commentary. Let me just state
unequivocally that inclusion/exclusion of a main effect should NOT be
determined based on whether a two-way interaction is statistically
significant. In general, one should include all lower level effects when
testing for upper level effects in regression modeling. There are certainly
cases where exclusion of a main effect is warranted (e.g., multivariate
analysis in the hierarchical modeling world), but your situation does not
appear to be one of them.

Ryan
On Tue, Sep 14, 2010 at 4:29 PM, Jose Rocha <
jose.ferreirinha.rocha@gmail.com> wrote:

> Bruce:
> Yes, I tried to include "sex" but it changed the results, and none
> coping*sex was significative (.05). I am out of office, tomorrow I will
> past
> the table of regression. That suggestion is great!
>
>
> Richard:
> It was the sex*coping6 that was significant. I guess you gave the answer
> about the reason the inclusion of "sex" alone gets less significant values.
> How can I include bonferroni correction?
>
> R B:
> Considering the type of coping variables, they are not binomial, they are
> continuous. And each subject has values for all 6 coping styles. Those
> results came from a specific scale/sub-scale scores.
>
> Thanks again for your nice comments and suggestions. I will follow this
> discussion with the table of regression coefficients.
>
> José
> --
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