Thank you! So the data has subjects that are were in 1 of 2 treatments and were offered 1 of 2 reward types (2x2 design). Both variables are nominal categorical. Please see my code below, I am using the overlayed survival plot, currently defined by SURVIVAL=_ALL_/DIRADJ GROUP=TREATMENT, but really I need the group to be TREATMENT*REWARD so that I get four lines, each representing the four categories of treatment*reward? Thanks in advance for your help!    PROC PHREG DATA=DATA PLOTS (OVERLAY)=SURVIVAL; CLASS TREATMENT REWARD; MODEL IS*IPF(0) = TREATMENT REWARD TREATMENT*REWARD BW / RISKLIMITS TIES=EFRON MAXITER=100; BASELINE OUT=REWSOCISBASELINE COVARIATES=TMAZE.REWARDSOCIAL OUTDIFF=REWARDSOCIALISOUTDIFF LOGLOGS=REWARDSSOCIALISLLS SURVIVAL=_ALL_/DIRADJ GROUP=TREATMENT; OUTPUT OUT=REWARDSOCIALISOUTPUT XBETA=REWARDSOCIALISXBETA STDXBETA=REWARDSOCIALISSTDERROR RESMART=REWARDSOCIALISMARTINGALERES RESDEV=REWARDSOCIALISDEVIANCERES RESSCH=REWARDSOCIALISSCHOENFELDIHE REWARDSOCIALISSCHOENFELDIHS REWARDSOCIALISSCHOENFELDPHE REWARDSOCIALISSCHOENFELDPHS DFBETA=REWARDSOCIALISDFBETA; HAZARDRATIO TREATMENT; HAZARDRATIO REWARD; HAZARDRATIO BW; ASSESS PH/RESAMPLE; RUN;    ... View more