burgman1995             Burgman, Grimson & Ferson (1995) combinatorial
                        persistence test
ede_estimate            Extinction date estimate
mcinerny2006            McInerny, Roberts, Davy & Cribb (2006)
                        sighting-rate persistence test
ole                     Optimal Linear Estimation of extinction date
robson1964              Robson & Whitlock (1964) truncation point
                        estimator
sighting_data           Construct a validated sighting record
solow1993               Solow (1993) nonparametric persistence test
solow1993b              Solow (1993b) declining-population persistence
                        test
solow2005               Solow (2005) sighting-effort-weighted
                        persistence test
strauss1989             Strauss & Sadler (1989) confidence interval for
                        the end of a range
strauss1989_curve       Full confidence curve for the Strauss & Sadler
                        (1989) estimator
