age (daily) model with variable intervals between sampling

[jclaisse]

I am trying to fit a (live recapture only) age model to see if survival rates increase with age (days old) in juvenile fish, but my intervals between sampling varies between every 2 to 4 days over a ~40 day period. So if I try to fit an age model using the pims like so:

Code: Select all

1 2 3 4 5 6 7
  1 2 3 4 5 6
    1 2 3 4 5
      1 2 3 4
        1 2 3

With intervals between sampling events being (2,2, 4, 3, 2, 3,2 days),
for example parameter 2 from row 1 represents a fish that is (2+2) = 4 days old, but in row 3 parameter 2 represents a fish that is (4+3) = 7 days old.

Is there a good way to overcome this issue? Could I somehow put the age(days old) for each indivdual at each sampling into the DM and model it that way? Or do some sort of Trend model?

I am also going to model Phi as a daily survival rate where just the initial interval is different from the rest:

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1 2 2 2 2 2
  1 2 2 2 2
    1 2 2 2
      1 2 2

And my thinking is that while I will loose precision because my initual time interval can be 2 to 4 days, in most cases it is 2 or 3 days and if the effect is strong over the first few days of life on the reef it will still show up.