st: ksm

[Constantine Daskalakis <constantine.daskalakis@mail.tju.edu>]

I'd like to report some unusual performance of the -ksm- command.

I have a binary outcome Y and a continuous predictor X. I wanted to do a 
lowess, separately for subgroups of data (by the variable Z, which takes on 
four distinct values in my data), so I tried the undocumented

. ksm y x, lowess by(z)

This actually worked fine, producing four plots on a single page (Z has 4 
separate values in my dataset).

But when I tried

. ksm y x, lowess logit by(z)

I got flat lines in all my graphs (something was not working). So, I 
figured, it's an undocumented feature, so I can't be picky.

But then, I tried to do the simple (and correct)

. ksm y x, lowess

and got an error message

by() invalid
r(198)

And this correct -ksm- specification would not work from then on.

Now this seems to be a bug. An incorrect invocation of -ksm- should not 
effect future correct specifications of the same command.

[By the way, a supported by() option would be very handy for -ksm-, so 
maybe Stata can implement one?]


But now I have a big problem in my hands.

Even when I quit Stata and restart, I keep getting the same error message 
with any (correct) specification of the -ksm- command.
And this still happens even if I reboot my computer!
In effect, I cannot use the -ksm- command any more.

I updated my version of Stata (hoping that an updated executable might 
solve this) but the problem persists.
It seems that I have to reinstall Stata from scratch.

What do I do?



________________________________________________________________

Constantine Daskalakis, ScD
Assistant Professor,
Biostatistics Section, Thomas Jefferson University,
125 S. 9th St. #402, Philadelphia, PA 19107
   Tel: 215-955-5695
   Fax: 215-503-3804
   Email: constantine.daskalakis@mail.tju.edu
   Webpage: http://www.kcc.tju.edu/Science/SharedFacilities/Biostatistics

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