Description Usage Arguments Details Value Author(s) See Also Examples

Estimates the probability of detection in a two-observer system when observations are independent.

1 | ```
F.double.obs.prob(df, observer = "both")
``` |

`df` |
A data frame containing the components |

`observer` |
A number of text string indicating the primary observer. Primary observers can be
observer 1, or observer 2, or "both".
If, for example, observer 2 was a data recorder and part-time observer, or if observer 2
was the pilot, set |

When `observer`

= "both", the observers are assumed to be independent. In this case the estimate
of detection is

*p = p1 + p2 - p1*p2*

where *p1* is the proportion of targets seen by observer 2 that were also seen by observer 1,
*p2* is the proportion of targets seen by observer 1 that were also seen by observer 2.
This estimator is very close to unbiased when observers are actually independent.

A single scalar, the probability of detection estimate.

Trent McDonald, WEST Inc., tmcdonald@west-inc.com

1 2 3 4 5 6 7 | ```
# Fake observers
set.seed(538392)
obsrv <- data.frame( obsby.1=rbinom(100,1,.75), obsby.2=rbinom(100,1,.5) )
F.double.obs.prob( obsrv, observer=1 )
F.double.obs.prob( obsrv, observer=2 )
F.double.obs.prob( obsrv, observer="both" )
``` |

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