Capture-Recapture Sampling/Examples/Arbitrary Example 1

Example of Capture-Recapture Sampling

Let $25$ squirrels be captured, marked and released.

On a later date, let $40$ squirrels be captured and inspected.

Let $5$ of those be ones which were marked on the first capture exercise.

Then a fair estimate of the entire population of squirrels is $200$.

Let:

$n_1$ be the number of squirrels captured, marked and released on the first round.

$n_2$ be the number of squirrels captured on the second round.

$m$ be the number of marked squirrels in the sample captured on the second round.

Then we have:

$\ds n_1$

$=$

$\ds 25$

$\ds n_2$

$=$

$\ds 40$

$\ds m$

$=$

$\ds 5$

$\ds \leadsto \ \ $

$\ds \dfrac {n_1 n_2} m$

$=$

$\ds 200$

$\blacksquare$