I would like to know how SPSS controls for variables in logistic regression in order to report the correct "controlled" OR.
The specific case which bothers my is as follows:
Lets say I have one IV tumor size which is either small tumor size or large tumor size the other IV is Risk classification with low risk and high risk.
My dependent variable is complications yes or no.
Unfortunately people with a high risk often also have a large tumor.
Now to assess the actual effect of the risk classification I used the layer tumor size and did a crosstab which gave me the OR for high vs low risk patients when they have large tumors and high vs low risk patients when they have small tumors.
I assumed this was the controlling of variables.
Subsequently I heard that, when one performs a logistic regression in spss under table "variables in the equation" the OR (Exp(B)) for each variable while controlling for the other variables is displayed.
Unfortunately these ORs do not match with the ORs of the corsstab version.
What is the difference in that case?
Thanks a lot, I appreciate your help!
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