Posted by
Judith Saebel on
Jan 03, 2007; 3:56am
URL: http://spssx-discussion.165.s1.nabble.com/Sign-on-regression-coef-tp1072952p1072960.html
Hi Lisa,
You might also want to look at Tabachnick & Fidell (2001, pp. 148-149),
part 5.5.4 (Suppressor variables).
Tabachnick, B. G. & Fidell, L. S. (2001). Using multivariate
statistics (4th ed.). Boston, MA: Allyn and Bacon.
(ISBN 0-321--05677-9)
Best of luck,
Judith
-----Original Message-----
From: SPSSX(r) Discussion [mailto:
[hidden email]] On Behalf Of
Lisa Stickney
Sent: Wednesday, 3 January 2007 13:25
To:
[hidden email]
Subject: Re: Sign on regression coef?
Hi William,
Thanks for the reply. I considered supression but the correlation
between the two IVs is .385 (p < .001). Is that high enough for
suppression? Also, I thought that a condition of suppression was that
the
suppressor variable be uncorrelated with the DV (in my case r = .176, p
<
.05). Is this incorrect? Thanks in advance.
Best,
Lisa
----- Original Message -----
From: "William B. Ware" <
[hidden email]>
To: <
[hidden email]>
Sent: Tuesday, January 02, 2007 9:30 PM
Subject: Re: Sign on regression coef?
> Lisa,
>
> Look at the correlation between the two IVs. I'm going to guess that
it
> is pretty large... I think that what you have is a case of
"suppression."
> Check out one of the older editions of Cohen and Cohen or Cohen,
Cohen,
> Aiken, and West for an explanation...
>
> wbw
>
>
________________________________________________________________________
__
> William B. Ware, Professor Educational
Psychology,
> CB# 3500 Measurement, and
Evaluation
> University of North Carolina PHONE
(919)-962-7848
> Chapel Hill, NC 27599-3500 FAX:
(919)-962-1533
> Office: 118 Peabody Hall EMAIL:
[hidden email]
> Adjunct Professor School of Social
Work
>
________________________________________________________________________
__
>
>
> On Tue, 2 Jan 2007, Lisa Stickney wrote:
>
>> 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]
>>
>