st: generating age variable

[Kim Price <kprice@hsph.harvard.edu>]

Hi,

I would like to create an age variable that subtracts each dob from a particular date.  I looked at the reference guides and web page, but they were not helpful in answering this question. I've tried the following, but they both create missing values. 

1) 
generate age=mdy(4,15,01-dob)/365.25 

and

2) 
generate smpdate=mdy(4,1,01);

format smpdate %d;

gen age=(smpdate-dob)/365.25;

Any suggestions will be greatly appreciated.

Thanks,
Kim