Growth of dragons
by
Ann Cowling
Statistical Consulting Unit, Australian National University

When animals are observed in the wild, researchers often have no control over the dates at which they are able to find and observe particular animals. Thus they make different numbers of observations on each animal and there are irregular intervals between sampling times. Grassland earless dragons were observed in the wild over four years. The researcher wished to know whether their growth varies with sex, site and year of hatching. We look at the impact of the irregular sampling times and numbers of observations on estimation of year of hatching and subsequent inference in a non-linear mixed model for the growth of these animals.

Date received: January 23, 2002