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Posted 05-10-2017 08:48 AM
(1997 views)

Attached is the cross tab of my dependent variable DONOR and independent variable BEC. If someone is in the BEC then they seem to donate 18.67 times more than if someone is not in the BEC. I ran a logistic regression:

proc logistic data=work.work;

class BEC (ref='0');

model donor(event='1') = BEC;

run;

and came up with 18.67 odds ratio and a C statistic of .50

Then, I included 19 more variables and ran the logistic regression again. This time, the odds ratio was .426 and the c statistic was .77.

Is something wrong with my model? It doesn't seem like .426 makes sense if you look at the cross tab.

Thank you for any help!

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That is 2x2 contingency table, you should not put PROC LOGISTIC on this data, use PROC FREQ or CATMOD instead.

```
data class;
set sashelp.class;
x=age>14;
run;
proc freq data=class;
table sex*x/ relrisk riskdiff;
run;
```

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If you only include one independent variable, that is called perfect predicted model.

Model would not be trusted .

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