Description Usage Arguments Details Value Author(s) Examples
The function can calculate the probability of a feature that occupies
a proportion theta
of the sampling area and where the sampling point density of the survey is
specified; the sampling point density needed to achieve a specified probability of detection, where
theta
is also specified ; or the value of theta
that will be detected with specified
probability and sampling density.Unless the feature is made of a large number of random segments
(see below for how to deal with this situation), these methods apply only when the pattern of points
in the sampling deisgn is random.
1 | detect.prop(statistic, theta=NA, pdetect=NA, ssize=NA)
|
statistic |
Describes what aspect of design you want calculated. The choices are |
theta |
Feature proportion. Not needed if |
pdetect |
Probability detection. Not needed if |
ssize |
Sample size. Not needed if |
The probability of detection is p = 1 - (1 - theta)^{N}
. Formulae for theta
and
N
are readily obtained from this formula. If the spatial pattern of the feature consists of lots of small,
random uniformly distributed fragments, then we can redefine theta = Na/A
where a
is the
area of the sampling unit and A
is the sampling area.In this situation, the probability of patch detection
applies no matter what the spatial pattern of points in the sampling design. Unlike detect
, detect.prop
works for vectors - so long as the input vectors are of the same length.
prob |
Probability of detection |
ssize |
Sample size |
prop |
Feature proportion |
Jon Barry: Jon.Barry@cefas.co.uk
1 2 3 | detect.prop(statistic='P', theta=0.02, ssize=80)
detect.prop(statistic='N', theta=0.02, pdetect=0.9)
detect.prop(statistic='F', pdetect=0.9, ssize=80)
|
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.