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help for ^trpois0^                                          (STB-47: sg102)
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0-Truncated Poisson regression
------------------------------


  ^trpois0^ depvar [varlist] [weight] [^if^ exp] [^in^ range]  
            [, ^l^evel ^it^erate^(^#^) ir^r ^off^set^(^var^)^]

^aweights^ and ^fweights^ are allowed; see help @weights@.
Results may be redisplayed by issuing the command with no 
arguments or options. 
  
Options
-------

^level(^#^)^ specifies the confidence level, in percent, for confidence 
intervals. The default is ^level(95)^ or as set by ^set level^.

^iterate(^#^)^ specifies the maximum  number of iterations that are allowed 
before results are presentedas if convergence had been achieved.

^irr^ reports estimated coefficients transformed to incidence ratios, i.e., 
e to the power of b rather than b. Standard errors and confidence intervals 
are similarly transformed. This option affects how results are displayed, 
not how they are estimated. ^irr^ may be specified at estimation or when 
replaying previously estimated results.

^offset(^varname^)^ specifies a variable that is to be entered
directly into the log-link function with coefficient constrained to be 1.

^ltolerance(^#^)^ specifies the maximum change in the log-likelihood 
function that can occur between iterations before convergence can be 
declared and defaults to 10 to the power of -7.


Results may be redisplayed by entering the command. Exponential form and 
C.I. level are allowed as options without reestimation.

Use: A 0-truncated Poisson model is appropriate when modeling count data
     which does not have values of 0. This is to be distinguished from
     datasets without 0 values, but which may have 0's. For example,
     length of hospital stay data (LOS) begins with patients having a
     LOS of 1. 0 values are not allowed. This is a situation where a
     truncated model is appropriate.

     
Examples
--------

 . ^trpois0 studytim died drug2 drug3, irr nolog^
 
 . ^trpois0 infected cases cd4 cd8, nolog irr off(cases) cluster(prov)^

 . ^trpois0, level(90)^    [redisplay]


Author
------

       Joseph Hilbe
       Arizona State University
       hilbe@@asu.edu


Also see
--------

   STB:  STB-47 sg102
Manual:  [R] poisson, glm, cnreg
On-line:  help for @poisson@, @glm@, @cnreg@