Date: Wed, 16 Apr 2008 12:54:37 0400
ReplyTo: Howard Alper <halper@HEALTH.NYC.GOV>
Sender: "SAS(r) Discussion" <SASL@LISTSERV.UGA.EDU>
From: Howard Alper <halper@HEALTH.NYC.GOV>
Subject: Getting odds ratios
Hi,
I'm doing a logistic regression where some of the independent variables
are yes/no1/0 indicator variables (numerical), but other independent
variables are left as categorical (age, race, etc.)
I'm interested in the odds ratios and confidence intervals. For the
indicator variables, the odds ratio is the exponential of the regression
coefficient, which is as it should be. But for the categorical variables,
the odds ratio is NOT equal to the exponential of the regression
coefficient. Can anyone explain this?
Also, if I include interaction terms among the categorical variables,
such as agesex, then NO information about the odds ratios for the
categorical variables appears at all (either the main terms or the
interaction.) How can I obtain this information (again, I wonder if
exponentiating the regression coefficients will give me the right answer.)
Thanks in advance,
Howard Alper
