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Re: Sign on regression coef?

Posted by Henrik Lolle on Jan 04, 2007; 1:41pm
URL: http://spssx-discussion.165.s1.nabble.com/Sign-on-regression-coef-tp1072952p1072956.html

Hi Lisa,

The phenomenon is also called for Simpson's Paradox (when the sign is
inverted and not just supressed). You can read more on:

http://plato.stanford.edu/entries/paradox-simpson/

Best,
Henrik


Lisa Stickney wrote:

> My thanks to all for your comments, help & insight.
>
>    Best,
>        Lisa
>
>
> ----- Original Message -----
> From: "Statisticsdoc" <[hidden email]>
> To: <[hidden email]>
> Sent: Wednesday, January 03, 2007 10:38 AM
> Subject: Re: Sign on regression coef?
>
>
>> Lisa,
>>
>> David's example is a good one.  Another example that comes to mind has
>> been
>> reported in research on self-esteem in early adolescence.  In a study by
>> David Dubois, peer self-esteem and academic self-esteem both correlated
>> with
>> students' academic performance, and with one another.  However, when both
>> academic and peer self-esteem were entered into a reqression equation to
>> predict students' academic performance, the beta weight for peer-self
>> esteem
>> is negative.  Students' who have high levels of peer self-esteem relative
>> to
>> academic self-esteem have poorer performance.  Illustratively, students
>> with
>> high peer and low academic self-esteem do poorly, while those who have
>> low
>> peer and high academic self-esteem perform well.  A key issue to examine
>> with supressor variables is the relationship between the unique variance
>> in
>> the predictors and the criterion variable.  In this example, the unique
>> variance of peer self-esteem (the portion that is not shared with
>> academic
>> self-esteem) has a negative association with acsdemic performance.  Such
>> situations can arise even when the predictor variables have a moderate
>> correlation (.4 to .5), depending on how the remaining unique variance is
>> associated with the criterion variable.
>>
>> 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?
>>
>> 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]
>>

--


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Henrik Lolle
Associate Professor
Department of Economics, Politics and Public Administration
Aalborg University
Fibigerstraede 1
DK 9220 Aalborg East
Home page:
http://www.socsci.aau.dk/~lolle/
http://www.socsci.aau.dk/institut2/dansk/empl/lolle.htm
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