help for wtddiag

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

Online: help for wtd, wtdml, wtdq