Question 2.1

What is TRIM, how does it work, where can it be obtained?


TRIM (TRends and Indices for Monitoring Data; Pannekoek & Van Strien, 2001) is the standard software tool we use to analyze time series of count data obtained from monitoring schemes and to produce estimates of yearly indices and trends. The analysis is based on loglinear Poisson regression (a form of generalized linear modeling). Such analyses are also available in standard statistical packages, but because TRIM is tailored to a selected set of models only, it runs faster and is easier to use.

TRIM is a freeware program, developed by Statistics Netherlands to be applied in wildlife statistics. It can be downloaded on