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Diagnostic plots for Waiting Time Distribution data

wtddiag,barsize(#)[cutpt(date)frmodels(fr_mods)hdmodels(rate_mods)cens(cens_type)noiesttwoway_opts]

wtddiagis for use with Waiting Time Distribution data; see help wtd. You mustwtdsetyour data before using this command; see help wtdset.

Notes on syntax

fr_modsis a string consisting of one or more of the letters 'e', 'l', and 'w' in arbitrary order.

rate_modsis a string consisting of one or more of the letters 'e' and 'u' in arbitrary order.

cens_typeis one of

depphi|dep|indep|none

twoway_optsare options fortwoway, see help twoway.

Description

wtddiagmakes 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 onwtdml, see help wtdml.

Options forwtddiag

barsize(#)specifies the width of bars in the histogram. The unit ofbarsize()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 thed() 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 forwtdml, see help wtdml.

noiestrequests 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