Subtract stratum understanding

[Eldar]

I am modelling year round transitions between sites: in summer all wintering sites are not available and in winter - breeding sites. Let's imagine that bird has no way stay in stratum A from t to t+1. It can only move to other stratas. So I'd like to fix this saying the Psi(At->At+1) = 0. But I can't do it as it is in subtract stratum. Way to go in this case would be to define another stratum for subtraction. But in my case all stratas have structural zeros at some time intervals.
Is it possible to create such model with mlogit link or do I need to switch to logit?
Eldar

[jlaake]

Eldar-

I cannot see anyway to use the mlogit link in that case but maybe someone more clever than I can think of a way. It sounds like part of the transition set is deterministic. What are your states?

--jeff

[Eldar]

Here is my design:

http://philomachus.ru/downloads/MStrata_design.jpg

The states are geographical locations that are more or less distinct.
Thanks,
Eldar

[Eldar]

Is it possible to change a subtract.stratum after making a ddl? I pretty sure that it is not possible but just in case there is a shortcut it would be great. Just don't want to spend hours again on setting Psis to 0.
Eldar

[jlaake]

Short answer is no and it would probably not be a good idea to modify the data values.

What do you mean by "Just don't want to spend hours again on setting Psis to 0."?

Are you doing that manually for some reason? You NEVER want to do any portion of the model build manually with RMark as it defeats the purpose of automation.

Are you removing design data or setting fixed values? Either way, you should be able to do it with code and it certainly shouldn't take hours unless I'm completely misunderstanding what you are saying.

--jeff

[Eldar]

Thanks Jeff,
I was deleting rows from ddl by a self written function with GUI... Now I understand that it was not a good idea - if you will need to repeat the task.