Date: Thu, 9 Feb 2006 21:14:00 -0700
Reply-To: Aric Zion <Aric.Zion@asu.edu>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: Aric Zion <Aric.Zion@asu.edu>
Subject: Re: Odds ratio question
Content-type: text/plain; charset=UTF-8
No, it means a 77% decrease in the odds (i.e. 1 - .23 = .77). If you think of it this way... that .866 means that a 1 unit change in x means that the odds gets multiplied by .866 (i.e. a 13.4% decrease), then compounding .866 ten times (i.e. .866^10) gives you .237 as an odds multiplier and 1 - .237 = .763.
From: SPSSX(r) Discussion on behalf of S Crawford
Sent: Thu 2/9/2006 8:01 PM
Subject: Odds ratio question
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.
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