Dear BUGSusers,
does anybody have an experience with doubly interval censored data in Bugs?
My data consists of pairs of intervals giving the onset (time when the
individual starts to be at risk) and death times. I.e. it is known that a
onset time A lies between u[1] and u[2] and a death time B lies between u[3]
and u[4], u[1] < u[2] and u[3] < u[4]. The quantity of a main interest is then
a difference D = B - A. There is no problem to assign a parametric
distribution to both time quantities A and B, and to use Bugs function I() to
indicate interval censored data.
e.g.
A ~ dweib(gammaA, lambdaA)I(u[1],u[2])
unew[3] <- max(u[3], A) ## to ensure that A < B
B ~ dweib(gammaB, lambdaB)I(unew[3],u[4])
D <- B - A
Program of this type works if for all individuals u[1] < u[2] < u[3] < u[4].
The problem occurs if some individual experiences both onset and death during
one interval, i.e. if u[1]=u[3] and u[2]=u[4]. In that case Bugs always
crashes.
Arnost Komarek
Biostatistisch Centrum K.U. Leuven
U.Z. St. Rafael
Kapucijnenvoer 35
B-3000 Leuven
Belgium
Tel : +32 - 16 - 33 68 86
Fax: +32 - 16 - 33 69 00
Web: http://www.med.kuleuven.ac.be/biostat/
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