I am looking to create a multi-strata file for a set of telemetry data. 100 tagged birds were released into my study area. At least two locations were obtained on each of these birds within the first two weeks post-release. Subsequently, due to personnel limitations, locations were obtained on a subset of about 40-50 birds. Birds were searched for and located every day if possible. Birds that went missing or died were replaced with birds randomly selected from the greater pool of birds available for tracking. Absence of a location for any bird within the subset can be attributed to 1 of two reasons:
Bird could not be located within the search area.
Bird was not within the subset of daily tracked birds at that point in time.
My question, is how does one deal with these ‘gaps’ in information when creating the multistrata file...Is it adequate to just place zeroes within all these gaps, even though search effort for some birds (those not within the subset of daily tracked birds) was nonexistent at those points while for others it was quite thorough....?
I would appreciate any advice/suggestions on this topic...
Thanks in advance,
KK
Multistrata Models
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Re: Multistrata Models
by bacollier » Tue Aug 16, 2011 2:42 pm
KK,
Saw no one had responded so I thought I would take a shot.
I guess I am unclear on your objective relative to the application of a multi-strata analysis, are you sure that is what you should be using? Based on what you have detailed below, it seems you have standard telemetry data from a known fate style radio-tracking study? Or are you interested in estimating transition probabilities for individuals entering/leaving your study area and perhaps moving to another study area? (which since you have known individuals, the % not on the location is the transition rate assuming no telemetry failures).
If a bird which was tracked but not located within the study area via radiotelemetry, then technically it was censored during the missing occasion and it would get a (assuming LD structure) "00" (censored), but if a bird was not tracked, it would get a ".." (not sampled).
Bret
Saw no one had responded so I thought I would take a shot.
I guess I am unclear on your objective relative to the application of a multi-strata analysis, are you sure that is what you should be using? Based on what you have detailed below, it seems you have standard telemetry data from a known fate style radio-tracking study? Or are you interested in estimating transition probabilities for individuals entering/leaving your study area and perhaps moving to another study area? (which since you have known individuals, the % not on the location is the transition rate assuming no telemetry failures).
If a bird which was tracked but not located within the study area via radiotelemetry, then technically it was censored during the missing occasion and it would get a (assuming LD structure) "00" (censored), but if a bird was not tracked, it would get a ".." (not sampled).
Bret
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