Simulate trends in Known Fate

[sixtystrat]

Is there any way to simulate a linear trend in survival rates in the Known Fate simulation routine? I tried to import a design matrix as my true model and Mark crashes when I do so. Thanks.
Joe

[gwhite]

Joe:
This is one of the "gotchas" that I don't know a good way around. The issue is that the Known Fate simulator does not keep animals in the sample for more than one occasion. So, you may think you are simulating data for 5 years as 1010101010 if the animal were to live all 5 years. However, MARK is actually generating a encounter of 1000000000 unless you have specified new animals to be released on occasions 2 through 5. In other words, even though an animal lives through the interval where it was released, it is not re-released into the next interval. The reason for this behavior is that I don't want to release an animal with a 3-year radio collar but have it survive for more than 3 years.

You can specify the number of animals to release on each occasion and approximately mimic what you want. For example, suppose you have a survival rate of 0.9. Release 100 animals on occasion 1, 90 on occasion 2, and 81 on occasion 3. But, the releases are the expected number of survivors, not the actual number of survivors.

So here is another work around -- use the Burnham joint live-dead data type to simulate and analyze data, but recognize that you can have animals out-living the life of their collar. Set p=1, r=1, and F=1 to make the Burnham joint live-dead equivalent to the known fate data type.

Gary

[cooch]

So here is another work around -- use the Burnham joint live-dead data type to simulate and analyze data, but recognize that you can have animals out-living the life of their collar. Set p=1, r=1, and F=1 to make the Burnham joint live-dead equivalent to the known fate data type.

Gary

See section 16.6 in 'the book'.

[sixtystrat]

Ok, thanks. One issue that I am having though is that to create a linear trend (annual), I have to use the design matrix. I set it up as follows for S with animals monitored monthly for 5 years:
1 1
1 1
...
1 1
1 2
1 2
...
1 2
1 3
1 3
...
...
1 5

I save that matrix and when I try to import it into the simulation as the true data type, MARK crashes. I want to simulate an

[sixtystrat]

Ooops! Disregard that last partial sentence.