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help for cpoisson                                                (Joseph Hilbe)
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Censored Poisson regression: survival parameterization

        cpoisson  depvar [varlist] [if exp] [in range] , censor(varname) [
             offset(varname) exposure(varname) cluster(varname) level(#)
             from(asis) irr robust nolog maximize_options survey_options]

        Note: the option censor must be included in the command. A censor
        variable must use the following numbers to indicate the type of
        censoring: 0 = left censored, 1 = not censored, -1 = right censored.

    aweights, fweights, iweights, and pweights are allowed; see help weights.

    cpoisson provides access to all maximize options; see help maximize.

    cpoisson provides access to all survey options; see help svy.


Description

    cpoisson fits a censored Poisson maximum-likelihood regression of depvar
    on indepvars, where depvar is a non-negative count variable.  The censor
    option is required. If no observations are censored, a censor variable
    with all 1's must be specified. Interpret parameter estimates as one
    would poisson.

    cpoisson acccepts all of the help maximize options, the constraint()
    option, and all survey options and capabilities documented in [SVY];
    including multi-level surveys; poststratification; and BRR, jackknife,
    and linearization VCE estimators.

    This program uses ml lf method.


Options

        +-------+
    ----+ Model +------------------------------------------------------------

    censor(cenvar) is required. Values of 1 indicate a non-censored, 0 a left
        censored, and -1 a right censored observation.

    offset(varname) specifies a varname in model with coefficient constrained
        to 1.

    exposure(varname) specifies a ln(varname) in model with coefficient
        constrained to 1.

    constraints(constraints) apply specified linear constraints.



        +-----------+
    ----+ SE/Robust +--------------------------------------------------------

    cluster(varname)

    robust specifies that the Huber/White/sandwich estimator of variance is
        to be used in place of the traditional calculation.  robust combined
        with cluster() allows observations which are not independent within
        cluster (although they must be independent between clusters).  If you
        specify pweights, robust is implied.

    vce(options) allowed. vce() supports robust, opg, and native.  vce does
        not support options bootstrap or jacknife, However, cpoisson does
        support the bootstrap and jacknife commands, so these modeling
        capabilities are allowed.


        +-----------+
    ----+ Reporting +--------------------------------------------------------
   
    level(#) specifies the confidence level, in percent, for confidence
        intervals of the coefficients; see help level.

    nolog suppresses the iteration log.


        +-------------+
    ----+ max options +------------------------------------------------------


    maximize_options: technique(algorithm_spec), [no]log, trace, hessian,
        gradient, showstep, shownrtolerance, difficult, iterate(#),
        tolerance(#), ltolerance(#), gtolerance(#), nrtolerance(#),
        nonrtolerance, from(init_specs); see maximize.


        +-------------+
    ----+ svy options +------------------------------------------------------

    survey_options are all available. See help svy




Author and support

    Joseph Hilbe, Arizona State University:  hilbe@asu.edu


Remarks

    cpoisson is a user authored program. Support is by author. See Hardin &
    Hilbe, Generalized Linear Models and Extensions, Stata Press for
    discussion. Related information can also be obtained at [R] poisson.


Examples
 Before examples 1
. gen byte cenvar = 1

 Before example 2
. replace cenvar = 0 if time<=3
. replace cencar = -1 if time>=50

    . cpoisson time hmo age, censor(cenvar) nolog irr

    . cpoisson time hmo age, censor(cenvar) nolog cluster(provnum)

    . bootstrap: cpoisson deaths smokes a2-a5, censor(cenvar)
        exposure(pyears) irr nolog

    . svyset psuid [pweight=finalwgt], strata(stratid)

    . svy: cpoisson zinc age age2 weight female black orace rural, censor(cv)
        nolog irr


Also see

    Manual:  [R] Poisson regression; [SVY] Svy: poisson

    Online:  help cpoisson  poisson