st: Re: Median survival times via Poisson model, using -margins- ?

[graupel75@gmail.com]

Apologies, the correct equations and source:

We computed mu as the unweighted average of these 18 death rates [Per
categorical from Poisson model]. The risk of death at time t, R(t),
was computed as R(t) = 1 - e ^ (-mu*t), where t was in years. Median
survival was computed by finding the value of t satisfying the
relation, R(t) = 1 - e ^(-mu * t) = 0.5.

(from Robbins AS, Whittemore AS, Van Den Eeden SK. Race, prostate
cancer survival, and membership in a large health maintenance
organization. Journal of the National Cancer Institute.
1998;90(13):986–90.)


cheers-
Andrew Lover
______________________________________________
Epidemiologist
Centre for Infectious Disease Epidemiology Research (CIDER)
Saw Swee Hock School of Public Health
National University of Singapore

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