An On-Line Workshop Using a Simple Capture-Recapture Experiment to
Illustrate the Concepts of a Sampling Distribution
Carl James Schwarz and Jason Sutherland
Simon Fraser University
Journal of Statistics Education v.5, n.1 (1997)
Copyright (c) 1997 by Carl James Schwarz and Jason
Sutherland, all rights reserved. This text may be
freely shared among individuals, but it may not be
republished in any medium without express written
consent from the authors and advance notification of
the editor.
Estimating the number of fish that return to spawn using capture-recapture methods.
Objectives
- to learn how a simple capture-recapture methods can be used to estimate the size of a wildlife population
- to learn about a sampling distribution
- to learn how the sampling distribution depends upon the sample size
Statistical Prerequisites
Student should know:
- the difference between a population and a sample
- the relationship between a sample proportion and the population proportion
- how to draw a dot plot or a histogram
- how to compute a sample mean and sample standard deviation
Equipment needed
Overview
As with human populations, it is often important to know the number of wildlife in a particular region.
For example, fisheries managers set quotas for fishers based on estimates of
the number of fish present.
Unlike human populations, it is impossible to conduct a census - the animals
just won't return census forms!
So then, how are wildlife numbers estimated? One common method is called capture-recapture where a set of animals are caught, tagged, and returned to the population at time 1. A while later, at time 2, a second set of animals is caught. Based on the number of tagged animals found in the second sample, biologists can estimate the size of the population.
In this workshop, you will examine a simple capture-recapture experiment often used in fisheries management to estimate the number of salmon that return to spawn.
Workshop organization
This workshop consists of 4 modules. It is suggested that each be completed before starting the next module. The modules are:
- Background information on salmon.
- Point estimation of the escapement.
- Using a sampling bowl to simulate the experiment.
- Using a computer simulation to investigate the properties of the method.
Developed by Carl James Schwarz and Jason Sutherland at Simon Fraser University
This workshop is part of a collection of SFU Statistics workshops which may be
accessed by pointing your web browser to
http://www.math.sfu.ca/stats/Innovation/workshopindex.html
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