%sysfunc(open(dataset)) using where clause doesn't seem to filter

[Bullfrog]

Hello:  Can someone help explain to me why this codeset returns a value of 19, instead of 9?  For some reason, it's not applying my where clause as I'd expect.

%let dsid = %sysfunc(open(sashelp.class (where=(Sex="F"))));

%let Gender_NOBS =%sysfunc(attrn(&dsid,NOBS));

%let rc = %sysfunc(close(&dsid));

%put Gender Count =  &Gender_NOBS;

Thanks!

[LinusH · Accepted solution]

From online doc:

NOBS

specifies the number of physical observations (including the observations that are marked for deletion). An active WHERE clause does not affect this number.

[ScottBass]

I've attached a macro I use to determine the number of observations for various scenarios.  Perhaps you'll find it useful.  You'll have to modify it to remove the call to %parmv.