Posted by
statisticsdoc on
Jan 03, 2007; 2:57am
URL: http://spssx-discussion.165.s1.nabble.com/Sign-on-regression-coef-tp1072952p1072961.html
Stephen Brand
www.statisticsdoc.com
Hi Lisa,
This is an instance of supression of one IV by another. X2 may have a
positive correlation with Y, but when X2 is entered into a regression
equation that already contains X1, the relationship between the residual
variance in X2 (after removing its shared variance with X1) and Y is
negative. This problem arises quite often when there is a high degree of
collinearity between the predictors, and is covered well by Cohen & Cohen
(1975), Pedhauzur, and others.
HTH,
Stephen Brand
For personalized and professional consultation in statistics and research
design, visit
www.statisticsdoc.com
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]]On Behalf Of
Lisa Stickney
Sent: Tuesday, January 02, 2007 8:51 PM
To:
[hidden email]
Subject: Sign on regression coef?
Hi SPSSers,
First off, Happy New Year to all. Next, my apologies for posting a
stats question & not an SPSS question, but I'm hoping someone can help me.
I have 3 variables: 2 independent & 1 dependent. When I look at the
correlation table, they all correlate positively with each other. However,
when I put them in a regression, the regression coefficient on one of the
independent variables becomes negative. Can anyone tell me when/why this
might occur? Thanks in advance.
Best,
Lisa
Lisa T. Stickney
Ph.D. Candidate
The Fox School of Business
and Management
Temple University
[hidden email]