capture recapture Flashcards
N
estimated population size
M
total number of marked
animals (first sample)
r
r = total marked individuals in the
second sample
n
total number of animals in
the second sample
Peterson method formula
N=M*n/r
what method to use with an non-closed population?
Jolly-Saber method
what method do you use when you capture multiple times?
Schnabel method
for which methods does the capture probability need to be uniform?
Schnabel and Peterson
how to know the confidence interval for Peterson?
First you do r/n (marked animals in second sample / second sample size). With this number, and the second sample size you can see the two confidence intervals in the graph with the lines.
what does it say when the mark recapture graph line goes downwards?
its a removal method
Confidence interval van N?
take the two numbers from the graph. both 1/number * M
constraints of capture recapture?
-Precision is notoriously low
-at least 5-20 of population should be marked
-often the sample size is too low
does the capture probability need to be uniform for Jolly Saber?
no, you can correct for it
Does the Schnabel mehtod provide confidence interval?
no, but you can configure them with a regression method
why would you use Schnabel or peterson instead of Jolly Saber in an open system?
individually marking is often impossible/ laborous and its easier to calculate. if you have a small timeframe you can assume closed population
