Ragged telemetry data with censored cases

[Miina Kovanen]

Hello,

My question is:
To analyse survival rate with individual covariates, when the data includes both censored cases and is ragged , is it correct/ best to apply the Nest Survival analysis so that for the censored cases only the period they were succesfully tracked is used (i.e. from the tagging until the last observation "alive") ?

If yes, of course, one should anyway consider the possible reasons for the tracking failures and any possible bias created in the results.

I have'nt so far found published studies with similiar data analysed with MARK, see also http://www.phidot.org/forum/viewtopic.p ... ght=ragged

My data:
I'm planning to analyse an extensive 3-year telemetry data on survival of adult birds with MARK. We captured and marked individualls once a year (around 60/year), followed their survival until death / end of the study / as long as we could track them. So, due to the realism created by the field conditions, wide study area, and length of the data, it includes both
- cases that are lost before the end of the study, i.e. fate is not known (censored cases)
- individually varying sampling periods (ragged data)

Any comments are welcome!

Regards, Miina

[filups21]

I realize it's probably much too late to help the original poster, but for other folks searching through this forum with the same question, this should answer your question:

As long as you KNOW the nest was alive on the last day checked, then it is okay to code the fate as successful. However, if the censoring is occuring BECAUSE of the radio's failure (e.g., a deer hit by a car that also destroys the radio), then you are going to get a survival estimate that is biased high. When data are censored, you either assume that the animal was still alive and the censoring was not associated with the animal's fate (and code the fate as alive), or else assume that the censoring occurred because the animal died, and code the fate as dead.
Either way, you have to make an assumption -- censoring of animals that disapper requires an assumption about either the independence of the fate and censoring, or the dependence of the fate and censoring.
Gary
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