{smcl}
{* *! version 1.0 19 Mar 2024}{...}
{vieweralsosee "" "--"}{...}
{vieweralsosee "Install stfform" "ssc install stfform"}{...}
{vieweralsosee "Help stfform (if installed)" "help stfform"}{...}
{viewerjumpto "Syntax" "stfform##syntax"}{...}
{viewerjumpto "Description" "stfform##description"}{...}
{viewerjumpto "Options" "stfform##options"}{...}
{viewerjumpto "Remarks" "stfform##remarks"}{...}
{viewerjumpto "Examples" "stfform##examples"}{...}
{title:Title}
{phang}
{bf:stfform} {hline 2} Functional form test for Cox Models

{marker syntax}{...}
{title:Syntax}
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{cmdab:stfform}
[{cmd:,}
{it:options}]
should be used afer {cmd: stcox}, the current dataset should be {cmd: stset} before using {cmd: stfform}.

{synoptset 20 tabbed}{...}
{synopthdr}
{synoptline}

{syntab:Optional}
{synopt:{opt nsim:ulation(#)}}  sets the number of simulated values for the cumulative martingale residuals. Default value is 1000.

{synopt:{opt nog:raph}}  forces stfform not to display the plots. 

{synopt:{opt nplot(#)}}  sets the number of simulations displayed in the plot. Default value is 20.

{synopt:{opt saving(name)}}  save the simulation data to filename; use replace to overwrite existing filename

{synoptline}
{p2colreset}{...}
{p 4 6 2}

{marker description}{...}
{title:Description} 
{cmd: stfform} performs test for the functional form and the adequacy of the exponential link function of a previously fit Cox model based on Lin, Wei and Ying (1993) . 

{pstd}

{marker options}{...}
{title:Options}
{dlgtab:Main}

{phang}
{opt nsim:ulation(#)}  sets the number of simulations for the cumulative martingale residuals. Default value is 1000.

{phang}
{opt nog:raph}  forces {bf:stfform} not to display the plots. 

{phang}
{opt nplot(#)}   sets the number of simulations displayed in the plot. Default value is 20.

{phang}
{opt saving(name)}   creates a Stata data file (.dta file) in long format. This dataset contains, for each variable, the values (variable {it: z}), the cumulative martingale residuals (variable {it: M}) and the simulated realizations of the null process  (varlist {it: W*}). Variables are identified by variable {it: var}.



{marker examples}{...}
{title:Examples}
    Setup
        {cmd: . webuse drugtr}
    Show st settings
        {cmd: . stset}
    Fit Cox proportional hazards model
        {cmd: . stcox drug age}
    Test the functional form 
        {cmd: . stfform}

{title:Author}
	Daniele Spinelli
	Department of Statistics and Quantitative Methods
	University of Milano-Bicocca, Italy
	daniele.spinelli@unimib.it
{p}