Modifies a proportional hazards model fitted by
RPHFIT (R.W. Payne).
|Controls printed output (
||How to change the model (
||Whether to pool terms in the accumulated summary generated by the fit|
||Model specifying the change|
This procedure allows you to modify the contents of a proportional hazards model that has been fitted by procedure
RPHFIT. The change to the model is specified by the
TERMS parameter. The setting of the
METHOD option specifies how the model is to be changed:
||adds the terms specified by the
||drops those terms from the fitted model; and|
||drops any terms specified by the
The default is
METHOD=add. Note, though, that any term that is to be added must have been included in the full model specified by the
MAXIMALMODEL option of
RPHFIT. By default the changes are made individually, one term at a time, so that each one will have its own line in an accumulated analysis of deviance. However, you can set option
POOL=yes to make them all at once.
FIT directive, except that there is an extra setting
loglikelihood to print -2 times the log-likelihood and the number of degrees of freedom in the model after the change. The deviance produced for the terms in the regression model can be assessed using chi-square distributions as usual, but the residual deviance is not usable as the maximal model assumed by the generalized linear models method is inappropriate. So, the residual line is suppressed in the summary and accumulated analysis of deviance.
Further details of the method used here (and by
RPHFIT) can be found in Aitkin et al. (1989).
None of the vectors must be restricted (and any restrictions will have been cancelled by
Aitkin, M., Anderson, A., Francis, B. & Hinde, J. (1989). Statistical Modelling in GLIM. Oxford University Press.
Commands for: Survival analysis.
CAPTION 'RPHCHANGE example',\ 'Data from Gehan (1965, Biometrika, 52, 203-223).';\ STYLE=meta,plain VARIATE [VALUES=1,1,2,2,3,4,4,5,5,8,8,8,8,11,11,12,12,15,17,22,23,\ 6,6,6,6,7,9,10,10,11,13,16,17,19,20,22,23,25,32,32,34,35] Time & [VALUES=24(0),1,0,1,0,1,1,0,0,1,1,1,0,0,1,1,1,1,1] Censor FACTOR [LABELS=!t(control,'6-mercaptopurine'); VALUES=21(1,2)] Treat FACTOR [LEVELS=42; VALUES=1...42] Subject RPHFIT [TIMES=Time; SUBJECTS=Subject; CENSORED=Censor; MAXIMAL=Treat] RPHCHANGE Treat