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help for ^stfracp^                           (STB-50: sg81.2)
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Fractional polynomial Cox proportional hazards models
-----------------------------------------------------


   ^stfracp^ xvar1 [# [# ...]] [xvar2 [# [# ...]]] [...] [xvarlist] [^if^ exp] [^in^ range] [, stcox_options fracpoly_options ]

   ^stmfracp^ varlist [^if^ exp] [^in^ range] [, stcox_options mfracpol_options ]


^stfracp^ and ^stmfracp^ are for use with survival-time data; see help @st@.
You must have ^stset^ your data before using this command; see help @stset@.

^stfracp^ and ^stmfracp^ share the features of all estimation commands;
see help @est@.

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


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

^stfracp^ and ^stmfracp^ estimate fractional polynomial proportional hazards
models. ^stfracp^ estimates a fractional polynomial transformation for one
variable (xvar1), whereas ^stmfracp^ estimates multiple fractional polynomial
transformations simultaneously.

Covariates other than xvar1, which are optional, are specified in xvar2, ...,
and xvarlist.  They may be modeled linearly and/or with specified fractional
polynomial transformations.  Fractional polynomial powers are specified by
typing numbers following the variable's name.  A variable name typed without
numbers following it is entered linearly.


Options
-------

stcox_options are any of the options for @stcox@.

fracpoly_options are any of the options for @fracpoly@.

mfracpol_options are any of the options for @mfracpol@.


Remarks
-------

^stfracp^ and ^stmfracp^ supply Stata with the necessary information to run
@fracpoly@ or @mfracpol@ with the @cox@ command. They are therefore convenience
tools.


Examples
--------

The commands

 . ^stset time cens^
 . ^stfracp x1, strata(z)^
 . ^stfracp x1 x2 -2 -1, strata(z)^
 . ^stmfracp x1 x2, strata(z) select(0.05)^

are equivalent to

 . ^fracpoly cox time x1, dead(cens) strata(z)^
 . ^fracpoly cox time x1 x2 -2 -1, dead(cens) strata(z)^
 . ^mfracpol cox time x1 x2, dead(cens) strata(z) select(0.05)^


Authors
-------

          Patrick Royston
          Imperial College School of Medicine, UK
          proyston@@rpms.ac.uk

          Gareth Ambler
          Imperial College School of Medicine, UK
          gambler@@rpms.ac.uk


Also see
--------

    STB:  STB-50, sg81.2 STB-49 sg81.1
 Manual:  [R] st stcox
	    [R] fracpoly
On-line:  help for @st@, @stcox@, @sts@, @fracpoly@, @mfracpol@