question and answer: missing values in MARK

[M M Marc Kery]

Dear Markers,

here is a question I had posted to the old forum, re-post here and add the answer suggested to me by Bill Kendall and Richard Barker. Thanks to both of them.

Q: Is there a missing value indicator in MARK ? Or are missing values allowed at all ?

A: Use constraints:
- set up the data so that it has three occasions at all sites
- make a group for those sites that in reality have three occasions and another group for those with two.
- constrain detection probability to zero for the non-existing occasion in the latter group

This is a fairly general way of dealing with missing values.

Kind regards -- Marc