SPSS Statistics

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  • 1.  Hi, Does anyone know how many independent variables can IBM SPSS Decision Trees contain?

    Posted Tue May 24, 2022 11:44 AM
    I'm trying to perform an analysis using IBM SPSS Decision Trees and wondering about some sort of restriction on the number of independent variables, since the data I use is large and may contain more than 1,000 independent variables.
    The product's documentation did not list an upper limit, so if anyone knows, I would appreciate it if you could let me know.

    Thank you.

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    清水 瞭
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  • 2.  RE: Hi, Does anyone know how many independent variables can IBM SPSS Decision Trees contain?

    Posted Tue May 24, 2022 12:07 PM
    Hi. I do not know of limitations for the TREE procedure other than these:

    • CHAID and Exhaustive CHAID: A categorical dependent variable may not have more than 126 categories. If the dependent variable is categorical, then the limit for a categorical predictor is also 126 categories.
    • CRT: A nominal predictor may not have more than 32 categories.
    • QUEST: If a predictor is nominal, then the limit for the dependent variable (which must be nominal) is 127 categories. A nominal predictor may not have more than 25 categories.
    Did you get an error message about a limitation? If not, then I would assume that the model is limited only by available memory.

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    Rick Marcantonio
    Quality Assurance
    IBM
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  • 3.  RE: Hi, Does anyone know how many independent variables can IBM SPSS Decision Trees contain?

    Posted Tue May 24, 2022 12:37 PM
    AFAIK, agreeing with Rick, there is no hard limit on the number of variables you can use with TREES, although the runtime would be substantial.  But I would be cautious if you are aiming at selecting just a small number out of 1000 or so.  Trees are notoriously unstable, so be sure to do aggressive cross validation.

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  • 4.  RE: Hi, Does anyone know how many independent variables can IBM SPSS Decision Trees contain?

    Posted Mon May 30, 2022 09:53 PM
    Hi, Rick & Jon.

    Sorry for the late reply and thank you for your answers and advice!
    Your answers have cleared up my questions for so far.
    If I get any error messages, etc., I will consult you again.

    Thanks a lot!!


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    R.. Sa
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