For correlated data, you would use ID statement. See: https://support.sas.com/documentation/cdl/en/statug/63962/HTML/default/viewer.htm#statug_phreg_sect056.htm When the proportional hazards assumption is not met, you would use STRATA statement. See: https://support.sas.com/documentation/cdl/en/statug/63033/HTML/default/viewer.htm#statug_phreg_sect019.htm and https://www.cibmtr.org/meetings/materials/crpdmc/documents/2010/feb2010/loganb_coxproportion1.pdf (page 7)
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