Repeated contrast for COXREG

Posted by Bruce Weaver on Jan 03, 2022; 10:00pm
URL: http://spssx-discussion.165.s1.nabble.com/Repeated-contrast-for-COXREG-tp5740927.html

Hello everyone and Happy New Year.  I just read a question on ResearchGate about the REPEATED contrast option for COXREG, and must confess that I am rather confused by the output that was attached to the question.  You can see it here:

https://www.researchgate.net/post/How_to_interpret_the_output_of_cox-regression_using_the_CONTRAST_subcommand_repeated

Here is what the v27 CSR manual entry for COXREG-CONTRAST says about Repeated contrasts:

"REPEATED. Comparison of adjacent categories. Each category of the independent variable except the last is compared to the next category."

The categorical variable in question has 4 levels.  Therefore, I would expect the following contrast coefficients for REPEATED contrasts:

Contrast 1: 1 -1 0 0
Contrast 2: 0 1 -1 0
Contrast3: 0 0 1 -1

But the output shows the following values:
Contrast 1: .750 -.250 -.250 -.250
Contrast 2: .500 .500 -.500 -.500
Contrast 3: .250 .250 .250 -.750

How can all levels be included in each contrast when "Each category of the independent variable except the last is compared to the next category"?  What am I missing here?  Do REPEATED contrasts behave differently for COXREG than they do for UNIANOVA/GLM?  Does it have something to do with the fact that COXREG does not include an intercept in the table of coefficients?  

Thanks to anyone who can explain what is going on here or point to some good resources.

Cheers,
Bruce