.-
help for ^stcoxe^                                                (STB-37: ssa9)
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Estimate Cox proportional hazards model (exact solution to ties)
----------------------------------------------------------------

       ^stcoxe^ [varlist] [^if^ exp] [^in^ range] [, ^nohr st^rata^(^varnames^) l^evel^(^#^)^
				^nosh^ow ]


^stcoxe^ is for use with survival-time data; see help @st@.  You must have ^stset^
your data before using this command; see help @stset@.

^stcoxe^ shares the features of all estimation commands; see help @est@.

To reset problem-size limits, see help @matsize@.


Description
-----------

^stcoxe^ estimates maximum-likelihood proportional hazards models.  ^stcoxe^
differs from ^stcox^ in that

    1)  ^stcoxe^ uses the exact calculation for failures occuring at the 
        same time; ^stcox^ uses the Peto-Breslow approximation.

    2)  ^stcoxe^ is slower and requires more memory than ^stcox^.

    3)  ^stcoxe^ does not provide the robust method of calculating the
        variance-covariance matrix of the estimators; ^stcox^ does.

    4)  ^stcoxe^ does not provide martingale or efficient score 
        residuals, nor does it provide estimates of the baseline hazard
        or survivor functions; ^stcox^ does.

Note that ^stcoxe^ does provide stratified estimation, as does ^stcox^.

^stcoxe^ and ^stcox^ produce identical results when there are no failures
occurring at the same time (no ties).


Options
-------

^nohr^ specifies that coefficients rather than exponentiated coefficients are to
    be displayed or, said differently, coefficients rather than hazard ratios.
    This option affects how results are displayed, not how they are estimated.
    ^nohr^ may be specified at estimation or when replaying previously
    estimated results (which you do by typing ^stcoxe^).

^strata(^varnames^)^ specifies up to 5 strata variables.  Observations with 
    equal values of the variables are assumed to be in the same stratum.
    Stratified estimates (equal coefficients across strata but baseline hazard
    unique to each stratum) are then estimated.

^level(^#^)^ specifies the confidence level for the confidence intervals of the
    coefficients; see help @level@.

^noshow^ prevents ^stcoxe^ from displaying the identities of the key st variables 
    above its output.  If this appeals to you, consider typing "^stset, noshow^"
    to make ^noshow^ the default for all st commands; see help @stset@.



Examples
--------

	. ^stset failtime died, id(patid)^

	. ^stcoxe drug age^
	. ^stcoxe drug age, strata(sex)^

	. ^stcoxe^


Author
------

     William Gould
     StataCorp.
     wgould@@stata.com


Also see
--------

    STB:  STB-37 ssa9
 Manual:  ^[U] 26 Estimation and post-estimation commands^
          ^[U] 35 Overview of model estimation^
On-line:  help for @est@; @stcox@, @lincom@, @lrtest@, @predict@, @test@, @testnl@, @vce@, 
                   @st@, @sts@, @stweib@; @st_rpool@