Date:         Fri, 10 Feb 2006 03:01:36 +0000
Reply-To:     S Crawford <sgthomson99@hotmail.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         S Crawford <sgthomson99@hotmail.com>
Subject:      Odds ratio question
Content-Type: text/plain; format=flowed

Hi, everyone.

I'm having problems with an odds ratio from a logistic regression.  We are
trying to predict a binary outcome (yes or no) based on one continuous
variable (variable X).  We get a significant overall regression.  The B
coefficient for this variable was -.144, and Exp(B) from the SPSS printout
for variable X was .866.

If we want to find out the change in odds for every 10 point increase in
variable X, do we just take:
.866 and raise it to the 10th power?

That would be .23 rounding off - so does that mean a 23% decrease in odds of
an abnormal outcome for every 10 point increase in variable X?

Many thanks for the help.

Susan

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