Tests and diagnostics for a proportional hazards model       [STB-19: ssa4]
------------------------------------------------------

        ^phtest1^ timevar varlist [^if^ exp] [^in^ range] [^, de^ad^(^deadvar^)^
                        { ^at(^time^)^ | ^div^ide^(^fraction^)^ } ^i^act^(^varlist2^)^ ]

        ^phtest2^ timevar varlist [^if^ exp] [^in^ range] [^, de^ad^(^deadvar^)^
                        ^at(^time^)^ ^i^act^(^varlist2^)^ ]

        ^phscore^ varlist ^, c^score^(^newvarlist^)^ [ ^d^ead^(^deadvar^)^ ^i^act^(^varlist2^)^ ]


calculate tests and diagnostics for a proportional hazards (PH) model. 
^phtest1^ and ^phtest2^ calculate a likelihood ratio test of the PH model
against a richer model that allows breakpoints in the hazard function.  A
significant test statistic is evidence against the PH assumption.  ^phscore^
calculates conditional and unconditional scores of a previously estimated PH
model.  The conditional scores are partial derivatives of the log likelihood
with respect to the variables in the ^varlist^.  The unconditional scores are
partial derivatives of the log likelihood with respect to each observation.
Under the PH assumption, each of these scores has an expected value of zero.


Author
------
	William H. Rogers, Stata Corporation
	FAX: 409-696-4601

Also see
--------
    STB:  ssa4 (STB-19)
 Manual:  [5s] survival
On-line:  ^help^ for ^survival^