6
Andrew Solow and Thomas Helser
One way in which auxiliary information can be incorporated into the methods
described here is through a Bayesian approach (Solow 1993a). It may happen in
practice that conditional prior information about T E given that T E < T is available.
For example, critical habitat may be disturbed or lost as a result of a hurricane.
Alternatively, more effective fishing technology may be introduced. Information
of this kind can be converted into a conditional prior distribution for T E and used
in a Bayesian test of H 0 against H 1 .
In applying the methods described here, it is important to think carefully about
the meaning of extinction. For example, in the applications described in the
previous section, due to the limited nature of the observation program, conclusions are limited both spatially and seasonally. Moreover, in this example, extinction may be related to temporary environmental changes (e.g., related to ocean
circulation), and the species may return in the future.
There are several possible extensions of this work. For example, Solow (1996)
considered the problem of testing for a common extinction time for two or more
species that are known to be extinct. This would be of interest in determining
whether the extinctions had a common cause.
Acknowledgments. The helpful comments of two anonymous reviewers are gratefully acknowledged.
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