st: Polychoric Correlation

[vinodsutaria@comcast.net]

Hi all:

 

I'm trying use polychoric command to get correlation between categorical variables. There are about 2000 observations. 

Gender: male=1 female=2   and stress: yes=1 and no=0

 

I'm getting this "conformability error".

 

polychoric  gender Stress
conformability error
r(503);

 

Why am I getting this error?  I'm using STATA 7.

Please advise me. Thanks

Vinod