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From |
Yoann Madec <yoann.madec@pasteur.fr> |

To |
Steve Samuels <sjsamuels@gmail.com>, statalist@hsphsun2.harvard.edu |

Subject |
Re: st: intcens: how to estimate mean and variance after intcens |

Date |
Fri, 26 Oct 2012 10:03:20 +0200 |

Thanks Steve for your messages. However, I may have to provide some clarifications. I used : stset date_deb_periode1, scale(365.25) origin(seroco_d)

In the help document regarding stpm, it is said:

------------------------------------------------------------------- Value of leftvar _d Meaning ------------------------------------------------------------------- . or _t 0 Right censored at _t . or _t 1 Event at _t 0 0 Right censored at _t 0 1 Interval censored, event in (0,_t] <_t 0 Late entry at leftvar, right censored at _t <_t 1 Interval censored, event in [leftvar,_t] -------------------------------------------------------------------

That worked ok.

Still: xi: stpm i.gender if num_v==1, stpmdf(6) scale(hazard) left(seroco_d) i.gender _Igender_1-2 (naturally coded; _Igender_1 omitted) seroco_d>_t in some observations While it is not true that seroco_d is >date_deb_periode1.

I hope someone can help. Yoann Le 26/10/2012 03:20, Steve Samuels a écrit :

If the origin of observation is truly seroco_d, your date of left censoring, then you do not have left-censored or interval-censored data. You have ordinary right-censored data. In that case, you can use -stpm2- (from SSC), which does not accept interval-censored data, but otherwise has some advantages over -stpm-. I suggest that study the section "Two concepts of time" in of the Manual entry for -stset- . Steve Steve On Oct 25, 2012, at 4:43 AM, Yoann Madec wrote: Thanks steve for your comments, and sorry not to have mention the source of the intcens command. After reading the help page for stpm, I still do not manage to make it work with interval-censored data. As a test, I have written: gen date_left_censoring=seroco_d stset date_deb_periode1, scale(365.25) origin(seroco_d) failure(hiv_controleur_bis) In this case, I should have no interval-censored data, but strictly right-censored data. However, here is what STATA states: . xi: stpm i.gender if num_v==1, stpmdf(6) scale(hazard) left(date_left_censoring) i.gender _Igender_1-2 (naturally coded; _Igender_1 omitted) date_left_censoring>_t in some observations I have been trying many things without success. I hope someone can help. Best regards, Yoann Le 12/10/2012 19:48, Steve Samuels a écrit :Yoann, The FAQ ask that you state the source of unofficial commands. -intcens- was written by Jamie Griffin and is available from SSC. The usual sample descriptive statistics cannot be calculated for interval-censored data. One approach is to apply Patrick Royston's command -stpm-, also at SSC, which fits flexible distributions. You can estimate survival curves and percentiles of the unconditional as well as covariate-conditional, distributions. You won't get standard errors for the percentiles, but you could -bootstrap- these. Means and SDs can be estimated with a lot more work, but I don't think these are useful descriptive stats for most survival data problems. In fact, I recommend -stpm-, not -intcens- for your main analysis. Some reasons: 1) Both fit parametric models, but -stpm- adapts to the shape of the distribution, saving you the need to select a "best" theoretical distribution. 2) -stpm- has excellent postestimtion options; -intcens- has none. (You can estimate survival curves& statistics starting with the supplied e(b) matrix, but you must do it by hand.) 3) -stpm- allows coefficients to vary with time (i.e. time-predictor interactions,); -intcens- does not. Steve On Oct 11, 2012, at 12:35 PM, Yoann Madec wrote: Dear Stata users, In order to describe the time to an event I used the command intcens. Indeed, for all my subjects, I know that the event took place within a time-interval, but do not have thje exact date. Using intcens, I vcan test whether some factors influence this time to event. However, I would like to summarize the time to event and provide a confidence interval for this time. I have not been able to fin how to estimate a mean and variance after intcens. i hope that someone will be able to help. Best regards, Yoann * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

* * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**References**:**st: intcens: how to estimate mean and variance after intcens***From:*Yoann Madec <yoann.madec@pasteur.fr>

**Re: st: intcens: how to estimate mean and variance after intcens***From:*Steve Samuels <sjsamuels@gmail.com>

**Re: st: intcens: how to estimate mean and variance after intcens***From:*Yoann Madec <yoann.madec@pasteur.fr>

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