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Re: logistic regression having problems with categorical variables

From: Werner
Subject: Re: logistic regression having problems with categorical variables
Date: Sat, 9 Jan 2016 10:53:44 +0000 (UTC)
User-agent: Loom/3.14 (

dr soumalya ray <drsoumalya-ray <at>> writes:

> hello friends,
> i'd like to point out a problem present in the "logistic regression"
function of PSPP.
> this is a problem stopping usage of PSPP for logistic regression analysis. 
> short description: while doing the logistic regression, pspp completely
ignores "measure" of the
> variable. it is treating categorical variable as a continuous variable
leading to wrong results.
> complete description:
> 1) for reporting this, i am using the example given in this SPSS tutorial- 
> 2) look at the example dataset - binary.sav
> 3) open the file.
> 4) it contains four variables. two nominal (admit and rank) and two scale
(gre and gpa)[visible in the
> "measure" of variable view].
> 5)go to: analyse -> regression-> logistic regression
> 6)select admit as the dependent variable and rank,gre and gpa as the
independent variable. 
> expected result: the output should look like this -
> actual result in pspp:
> 7) possible reason: pspp ignores the measure indicator of the variable. it
treats rank as a continuous
> variable. 
> 8) this is a long term problem and it exists since the function is
available in pspp. did not report it as was
> unable to confirm the expected result from SPSS. 
> 9) interestingly, if this file is imported in R and logistic regression
analysis done, expected result
> takes place. 
> pspp version: psppire 0.8.5 (problem present since logistic regression
function added in PSPP)
> uname -a:Linux som 4.2.0-21-generic #25~14.04.1-Ubuntu SMP Thu Dec 3
13:55:58 UTC 2015 x86_64 x86_64
> x86_64 GNU/Linux
> regards,
> som

Dear Som,

please try to run the analysis by using the syntax and not from the menu:

logistic regression admit with gre gpa rank 
   /categorical = rank.

Then PSPP should produce the same results as SPSS. I have tried it. 

Hope I could help.


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