Date: Tue, 12 Aug 2003 07:10:16 0500
ReplyTo: Anthony Babinec <tbabinec@ameritech.net>
Sender: "SPSSX(r) Discussion" <SPSSXL@LISTSERV.UGA.EDU>
From: Anthony Babinec <tbabinec@ameritech.net>
Subject: Re: Logistic Regression Chi Square to Effect Size?
InReplyTo: <p06001a03bb5d5871e4c5@[131.123.236.181]>
ContentType: text/plain; charset="usascii"
David  Presumably, the 95%CI bounds refer to the estimated parameter.
To aid interpretation, the regression coefficients from
Logistic regression are often exponentiated. It is
unclear from what is reported whether the 95%CI values
are in the metric of b or exp(b). If you can resolve
that, then consider the scale and range of the predictor
in question. For example, if the predictor in question is
Age, and the coefficient in question is exp(b)=1.1, then
a difference of, say, 10 years on the predictor in question
translates into an odds shift of 1.1^10 = 2.6. That
gives an indication of effect size.
Anthony Babinec
Original Message
From: SPSSX(r) Discussion [mailto:SPSSXL@LISTSERV.UGA.EDU] On Behalf Of
David M. Fresco
Sent: Monday, August 11, 2003 9:28 AM
To: SPSSXL@LISTSERV.UGA.EDU
Subject: Logistic Regression Chi Square to Effect Size?
Dear SSPS List members,
I am reading a journal article and am trying to decipher its findings. The
authors have a sample of 312 who either responded or did not respond to a
treatment. Using logistic regression with response status as the DV, the
authors have two continuous predictors of outcome. The first one is a
covariate and the second IV is of interest. Here is how the authors
describe their findings for the second predictor: p=0.0413;
chisquare=6.391; Coef/SE=2.041; 95%C.I.=1.0211.176.
I would appreciate some help interpreting this statistically significant
finding in terms of an effect size. Thanks in advance. Please cc any
replies to my email as I take the digest.

David M. Fresco, Ph.D. fresco@kent.edu
Department of Psychology Voice: (330) 6724049
Kent State University Fax: (330) 6723786
315A Kent Hall
P.O. Box 5190 http://dept.kent.edu/psychology/
Kent, OH 442420001 http://www.personal.kent.edu/~dfresco/
ListOwner of Helplessness http://psych.upenn.edu/~fresco/helplessness.html
Listowner of Mindfulness http://listserv.kent.edu/archives/mindfulness.html
