The statistical program for calculating population trends and indices based on monitoring data has been rewritten in the statistical program R.
TRIM was originally developed some 25 years ago by Statistics Netherlands (Pannekoek and Van Strien, 1991) and was made available as a freeware stand-alone program. Although the program has had several updates since then, the original programming language has become outdated and rendered further developments. That is why Statistics Netherlands decided to rebuilt TRIM as a package for the freely available and widely used open source statistical program R: RTRIM.
RTRIM contains the same methods and models for nature monitoring data as the original versions of TRIM. It can still work with the same input data and produces exactly the same output data, but as a package in R it can easily be integrated in other R programming processes. As a result of this there is a wider choice in how input data is provided, in how options and settings are chosen and how and what output is provided. New in this version is also the in-built possibility to combine results from other TRIM runs, e.g. to combine results obtained from the analysis of regions of a country into a single new output with a combined trend, indices and standard errors.
Being developed as R-package TRIM is as good as new and is made available for further developments by the large R-society. A development Statistics Netherlands is already working on, is making TRIM suitable for the use of multiple data per year (such as monthly counts). The renewed TRIM is available as RTRIM package on CRAN (Comprehensive R Archive Network).
Users of BirdStats cannot yet use this in combination with RTRIM, but we are working on a solution for that too.
Manual, documentation and helpfiles in the R environment with several programming examples can be found on the webpage http://cran.wustl.edu/web/packages/rtrim/index.html. For any questions about the use of RTRIM, please contact rtrimcbs.nl.
See more info about TRIM also on the website of Statistics Netherlands.
Tom van der Meij, on behalf of the team from Statistics Netherlands