I want to perform a multivariate cox regression analysis with 7 covariates (of which 4 categorical). I followed this online guide step by step as I am new to SPSS (https://www.scalestatistics.com/cox-regression.html). I got my data but I noticed that the '0=unkown' category of my covariates was being selected as the reference group, which I don't want. Now in the online guide I followed it stated I could select the 'change' button to "to use the lowest level of the categorical variable as the reference category", I am not sure if this would solve my problem but even if it would I then face the problem that I do not see this 'change' button anywhere. When clicking on the '?' button it brings be to the ibm site where you can also select the version of SPSS (I am using version 29.0.0.0 (241)) where it also mentions this 'change' button. If this would indeed solve my problem, where could I find this button, and if would not, what should I do?

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Alexis Maagdenberg
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#SPSSStatistics

Hi.

I can answer at least one of the questions you have. The "Change" button has been removed and the same functionality inserted into the radio selection in the dialog. Just clicking on a radio selection ("First" or "Last") changes the keyword "(first)" and "(last)" respectively.
As for the other question, I do think it would solve your problem.

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Rick Marcantonio
Quality Assurance
IBM
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