dr soumalya ray <drsoumalya-ray <at> yahoo.co.in> 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- > http://www.ats.ucla.edu/stat/spss/dae/logit.htm > 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 - http://i.imgur.com/W5Q4lTI.png > > actual result in pspp: http://i.imgur.com/IEyOUnO.png > > 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. Werner _______________________________________________ Pspp-users mailing list Pspp-users@gnu.org https://lists.gnu.org/mailman/listinfo/pspp-users
