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I am running a logistic regression in SPSS with a sample that uses survey weights. The sample size is 1000 and the weights are along the lines of .86 or 1.23 depending on the case. I am using the weights option in the Data command to weight my sample before I run my logistic regression but then I get the unweighted frequencies in the Categorical Variables Coding part of the output.

At the beginning my output gives me a Case Processing Summary, which says Unweighted cases with a superscript "a" which then says "If weight is in effect see classification table for the total number of cases." My classification tables all are properly saying 1000 cases which is right. I have 7 predictor variables (all categorical) and one outcome variable (dichotomous). My output seems to make sense, but I am troubled that the frequencies are all the unweighted frequencies. Are my results still legitimate? I am afraid that I may not understand the weighting quite properly.

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  • $\begingroup$ This appears centred on what SPSS does exactly. If the question is at heart statistical, please rephrase it to make that clear. $\endgroup$ – Nick Cox Jan 20 '14 at 18:26
  • $\begingroup$ How are you using the weights? You should be using complex samples, not weight cases. $\endgroup$ – Jeremy Miles Jan 20 '14 at 18:31
  • $\begingroup$ I think this question could be sufficiently statistical to be on-topic (cf, interpretation-of-rs-lm-output). @KristenLindSeal, perhaps you could paste some images of your output & ask for help interpreting it in line w/ your questions. $\endgroup$ – gung - Reinstate Monica Jan 20 '14 at 18:45
  • $\begingroup$ Actually this method does not properly handle survey weighting estimation -- it simply treats a weight of e.g. 100 as though it were 100 cases, but doesn't correctly estimate variances (and hence standard errors). See my answer to another question on using SPSS for weighted data here for more detail. $\endgroup$ – James Stanley Jan 20 '14 at 20:25
  • $\begingroup$ The CSLOGISTIC procedure handles survey weights. $\endgroup$ – JKP Jan 21 '14 at 3:12

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