PopSize simulates using mark-recapture sampling for estimating population sizesz. It has a very simple interface with only two displays, one that lets the user specify a number of parameters and the other where you perform the sampling experiments. You can choose between two different estimation techniques, set the population size, the number of individuals to mark and to recapture, and a number of other parameters that will affect the estimate such as the mortality of marked and unmarked individuals. You can also choose several different ways of estimating confidence limits around the estimates. Once the parameters are set up, you can simulate multiple rounds of marking and recapturing with the same parameters. One graph shows the estimated population size with confidence bars for each sample taken, while another graph builds a histogram of estimated population sizes as the user takes more and more samples. There is good online help on each parameter for students that want additional information, and the author includes accompanying written material from his own use of the program if you want to adopt his labs.

This is a nice, single-purpose program that should be useful in classes that discuss mark-recapture sampling. Though not flashy, the interface is functional and arranged well. The graphs make an effective demonstration of how different samples with exactly the same underlying dynamics can come up with different answers, and after many samples the histogram starts to look like a nice normal curve. Students can also get a feel for how different parameters make population estimates better or worse. I expect that this program would be most useful in upper level courses where students are taught enough about mark-recapture sampling that they have an understanding of how it works before using the program. The author also recommends using PopSize in conjunction with a field component where students actually do some sampling.

Computer: DOS, Windows

Source: Robert Gendron
Indiana University of Pennsylvania
email: rgendron@grove.iup.edu
web site: http://www.iup.edu/~rgendron/software.htmlx

Cost: Free

Last update 27nd of February 1999