Diagnostic plots for Waiting Time Distribution data
wtddiag, barsize(#) [cutpt(date) frmodels(fr_mods) hdmodels(rate_mods) cens(cens_type) noiest twoway_opts]
wtddiag is for use with Waiting Time Distribution data; see help wtd. You must wtdset your data before using this command; see help wtdset.
Notes on syntax
fr_mods is a string consisting of one or more of the letters 'e', 'l', and 'w' in arbitrary order.
rate_mods is a string consisting of one or more of the letters 'e' and 'u' in arbitrary order.
cens_type is one of
depphi | dep | indep | none
twoway_opts are options for twoway, see help twoway.
Description
wtddiag makes a histogram of the observed Waiting Time Distribution and allows adding both an ad-hoc estimate based on a chosen cut-point as well as parametrically fitted density/ies based on wtdml, see help wtdml.
Options for wtddiag
barsize(#) specifies the width of bars in the histogram. The unit of barsize() is days.
cutpt(date) specifies the cut-point after which all observed events are considered to arise from incident subjects. A vertical line is added to the plot at the cut-point, together with a horizontal line indicating the estimated incidence level. Finally, a table is displayed with information on estimates of prevalence and incidence based on the chosen cut-point. The date must be specified with syntax acceptable by the d() function, see help dfcn.
frmodels(fr_mods) specifies the forward recurrence densities used in defining the models to be fitted. 'e' denotes Exponential, 'l' Log-Normal, and 'w' Weibull, see help wtdml.
hdmodels(rate_mods) specifies the densities used for incidence and exit rates in defining the models to be fitted. 'e' denotes Exponential and 'u' Uniform, see help wtdml.
cens(cens_type) specifies the dependency structure between event and exit times and follows the syntax for wtdml, see help wtdml.
noiest requests display of maximization process(es) and output(s).
Examples
. wtdset event exit, i(id) start(31dec1996) end(31dec1997) scale(365)
. wtddiag, barsize(14) cutpt(1oct1997)
. wtddiag, barsize(14) frmodels(ew) hdmodels(e) cens(depphi)
. wtddiag, barsize(14) saving(diagplot.gph) /* save copy of plot */
Also see