Re: PSPP-BUG: Logistic Regression bugs

[John Darrington]

You are right.

As you may have noticed, the logistic regression feature is still in 
development.

As of the version you mentioned, the /CATEGORICAL subcommand was not 
implemented,
but it has been since, try the most recent HEAD.

I think there may still be a problem with missing values in the categorical
variables, and I am working on that.  Missing values in the non-categorical
predictor variables should be ok though.

I'm unsure exactly how it should behave in response to missing values on the
dependent variable.  The spss documentation says:
 "For a case with a missing value on the dependent variable, predicted values
  are calculated if it has non-missing values on all independent variables."
This statement doesn't make sense to me.  Why would a predicted value be
calculated? from what?  - I'm still thinking about that ...  Have you any
idea?

So thanks for your feedback.  I appreciate you taking the time to test and
report these things.

If you can do some similar tests with a very recent version (
3cd65292e3cc6bd6532214dcc8c8ddc65bdc2972 or later, I would appreciate it).

Particularly, more tests with missing values and with weighted values would
be great.

Regards,

John

On Tue, Nov 13, 2012 at 01:08:19PM -0500, Renan Levine wrote:
     Dear PSPP users and programmers,
     
     Thank you for your hard work in developing new capabilities for
     PSPP. I'm using the most recent version of PSPP, psppire.exe
     0.7.9-gaef7f5
     
     I recently encountered some problems while running logistic regressions:
     
     1) There appears to be a bug in the logistic regression routine
     that causes it to recognize missing values in the dependent
     variable as a value category. So, even when a variable is coded
     0, 1 and [system] missing (common in public opinion data), PSPP
     gives an error message: "Dependent variable's values are not
     dichotomous."
     
     I've run logit analyses on three different .por and one .sav
     datasets, tried to see if user-missing is treated differently
     than system-missing, and if declaring missing values works any
     differently than a recode statement. The only way I manage to run
     a logistic regression is if I recode the dependent variable to be
     two integers with no missing values.
     
     2) Less critically, I'm not sure the syntax /CATEGORICAL=var is
     working correctly. When I include that line, letting the computer
     know that an independent variable is dichotomous, I get an error
     message: .3-13: error: Syntax error at 'categorical'. HOWEVER,
     just including the variable on the initial line with the other
     independent variables seems to work (I can't be certain because I
     did not cross-reference my results with another statistics
     program).
     
     Yours,
     Renan
     


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