Instability in mortality estimation schemes related to stage-stuctured models

Current methods of mortality estimation from stage-structured population data fail to extract the detailed mortality information required by field workers. It has been suggested that the formalism of stage-structure population modelling might resolve the problem. Using this approach we derive a per capita death-rate estimator which is robust to sparse and noisy data, but show that there are fundamental instabilities limiting the application of such estimators. We demonstrate that our estimator is useful in prescribed circumstances and discuss the implications of our results for other estimation schemes.