cooch wrote:The trick is to consider the classical RD as a mixture of closed abundance and open population modeling. Since the GOF doesn't apply in the usual sense for the closed part (see relevant sections of chapter 14), then the problem can be reduced down to an open population problem. So, one approach that seems to be fairly robust (in many cases) is to simply collapse your secondary samples to a simple binary variable (seen, not seen), and do a GOF on the resulting encounter history - i.e., collapse the secondary closed samples to a single sample (seen once or not), then treat it like a CJS model, and do the GOF on that.
Bill Kendall has thought more about this than anyone else (no surprise there) - but until he weighs in to correct the approach I've described (which has seen some application) - thats what I suggest you try.
Thanks for the suggestion. I have tried this approach and while I get an estimate
of median c-hat for the fully time-dependent CJS model (no groups or anything fancy),
- Code: Select all
Estimated c-hat = 1.3451563 with sampling SE = 0.0090726
95% Conf. Interval c-hat = 1.2839771 to 1.4063354
One-sided 95% Upper Bound on c-hat = 1.3943265
Beta Variance-Covariance Matrix
3171.8494690 -2378.8760775
-2378.8760775 1784.1742311
the results
of the known fate model are odd:
- Code: Select all
95% Confidence Interval
Parameter Estimate Standard Error Lower Upper
------------------------- -------------- -------------- -------------- --------------
1: 1.0000000 0.1486852E-007 1.0000000 1.0000000
Is this partial convergence failure or nothing to worry about? I would not think I'd have such an issue with a fairly simple model, compared to the
robust design stuff.
Thanks,
Nate