Date: Fri, 19 Apr 1996 14:19:58 GMT
Sender: "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From: Candy Kane <c.kane@FERTILE.COM>
Organization: Growing greener every day
Subject: Re: Event-history problem
Ted Greenstein <Ted_Greenstein@ncsu.edu> wrote:
>I'm analyzing some data on marital stability. I have two waves of a panel,
>where the waves are separated by about five years. The unit of analysis is
>the married couple; I start out with about 5,000 couples who were married
>prior to wave 1, and my outcome variable is whether they are still married at
>wave 2. If their marriages terminated between wave 1 and wave 2, I have data
>on the date; if they were still married at wave 2, I know the date at which
>they were right-censored.
>One problem that has arisen is the fact that the couples are of varying
>marital durations prior to wave 1. That is, some of the couples got married
>30 years prior to wave 1, some 20 years, and so forth. Obviously, I need to
>take this into account in my model (I've been using a piecewise exponential
>model with LIFEREG). So far, I've been including an indicator of this prior
>marital duration in the LIFEREG model, and the results seem reasonable. As
>might be expected, prior marital duration is negatively related to the hazard
>rate of experiencing divorce at all durations.
>Does this procedure (controlling for prior marital duration) seem reasonable?
>Or there some trap I'm not seeing? Any comments or suggestions would be
It's not really clear from your post what your actual research
question is. Are you simply trying to model divorce rate as a function
of marriage duration? Or are there predictors you haven't mentioned?
The data you seem to have are these: a date of marriage for 5000
couples, and either a divorce date or a censoring date corresponding
to the earlier of a death date or date of collection of Wave 2.
It seems to me that modelling divorce rate here is a straightforward
process of subtracting the marriage date from the
divorce/death/censoring date to generate a response time, and
classifying divorces as events, and other cases as censored at the
earlier of death/Wave 2. You can then use either a parametric method
(proc lifereg) or non-parametric (proc lifetest) survival analysis to
generate your divorce hazard function.
Have I missed the point of the project here?!