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From | John Simpson <john.simpson@ualberta.ca> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: Correct modeling procedure for a population growth model that includes extinction? |
Date | Sat, 20 Feb 2010 09:55:21 -0700 |
I am interested in building a model that can provide a population growth curve over the range of environmental conditions covered in the samples.
The problem is that not every population survive through the entire period; populations go extinct with increasing frequency as the harshness of the environmental conditions are increased. This creates an unbalanced dataset and I am not sure how to handle this result without biasing the results.
1. Since the population sizes are not missing at random (MAR) it seems that xtmixed may not be appropriate. This missing data can be overcome using tsfill and carryforward, but I worry that this will unduly bias the results.
2. Since there are mixed effects it seems that xttobit may not be appropriate even though it allows for the treatment of truncated and censored data.
Any suggestions on how to proceed would be appreciated. Any direction towards relevant literature or research would also be appreciated.
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