*** *** Mayo Model Variables *** *** 1. age in years *** *** 2. albumin gm/dl *** *** 5. serum bilirubin mg/dl *** *** 8. edema treatment 0 = none and no treatment *** .5 = edema but no treatment, *** or edema resolved *** by treatment *** 1 = edema despite treatment *** *** 10. time days between *** registration and earlest of *** death, liver transplantation *** and July 1986 *** *** 12. prothrombin time seconds *** *** 16. stage 1,2,3,4 *** . = missing *** *** 17. censoring 1 = death *** 0 = other *** infile age albu bili edema time proth stage status using mayo_sub.dat label variable time "time (days)" label variable status "status" *** *** recode *** generate logalb = log(albu) generate logbil = log(bili) generate logpro = log(proth) recode stage 9=. *** *** EDA for predictors *** summarize logalb centile logalb, centile( 10 25 50 75 90 ) summarize logbil centile logbil, centile( 10 25 50 75 90 ) summarize age centile age, centile( 10 25 50 75 90 ) summarize logpro centile logpro, centile( 10 25 50 75 90 ) *** *** this defines the failure outcome *** stset time, failure(status) *** *** look at proportionality for logpro groups *** generate procat = logpro recode procat min/2.2999=1 2.30/2.3999=2 2.40/max=3 label variable procat "Categories of log(prothombin)" label define plab 1 "log(pro)<2.30" 2 "log(pro) 2.30-2.39" 3 "log(pro)>=2.40" label values procat plab tabulate procat stphplot, by(procat) *** *** Cox regression *** stcox logbil logalb age logpro edema, nohr scaledsch(resid0*) esr(esr*) *** Model checks stphtest, detail stphtest, plot( logbil ) stphtest, plot( logalb ) stphtest, plot( age ) stphtest, plot( logpro ) stphtest, plot( edema ) *** *** compute delta-betas *** set matsize 400 mkmat esr1 esr2 esr3 esr4 esr5, matrix(esr) mat V = e(V) mat Inf = esr*V svmat Inf, names(dfb) label var dfb1 "dfbeta log(bili)" label var dfb2 "dfbeta log(albu)" label var dfb3 "dfbeta Age" label var dfb4 "dfbeta log(prot)" label var dfb5 "dfbeta Edema" graph dfb1 time, yline(0) graph dfb2 time, yline(0) graph dfb3 time, yline(0) graph dfb4 time, yline(0) graph dfb5 time, yline(0)