Capture/Recapture

1
Capture/Recapture

• Imagine you have a population and you want to
  know how big it is BUT it is unrealistic to count
  the animals in the population.

2
A population of fish...
3
Take a sample
4
(No Transcript)
5
Count the number in your sample and Mark or Tag
6
7
7
Release the sample
8
(No Transcript)
9
(No Transcript)
10
Now capture a second sample

• Note how the proportion of tagged fish in this
  new sample

11
(No Transcript)
12
3/10
13
3/10 in the second sample should be approximately
the same as the fraction of the tagged fish in
the population.