Indicator power calculation of Halme et al. (2009)
or the congruence between indicator and target species.
Usage
indpower(x, type = 0)
Arguments
x
Community data frame or matrix.
type
The type of
statistic to be returned. See Details for explanation.
Value
A matrix with indicator species as rows and
target species as columns (this is indicated by the first letters of the
row/column names).
encoding
UTF-8
Details
Halme et al. (2009) described an index of indicator power defined as
$IP_I = \sqrt{a \times b}$, where $a = S / O_I$ and
$b = 1 - (O_T - S) / (N - O_I)$.
$N$ is the number of sites,
$S$ is the number of shared occurrences of the indicator ($I$)
and the target ($T$) species. $O_I$ and $O_T$ are number
of occurrences of the indicator and target species. The type
argument in the function call enables to choose which statistic to
return. type = 0 returns $IP_I$, type = 1 returns
$a$, type = 2 returns $b$.
Total indicator power (TIP) of an indicator species is the column mean
(without its own value, see examples).
Halme et al. (2009) explain how to calculate confidence
intervals for these statistics.
References
Halme, P., Mönkkönen{Monkkonen}, M., Kotiaho, J. S,
Ylisirniö{Ylisirnio}, A-L. 2009. Quantifying the indicator power
of an indicator species. Conservation Biology 23: 1008--1016.
See Also
indval (package labdsv) for the
indicator species analysis of Dufrêne{Dufrene} & Legendre.
Function beals estimates individual cell probabilities
of species occurrences.