Performs chi-squared tests for Fisher's aggregation indices (computed with
either count or incidence data). If another kind of data is provided, the R
standard chisq.test function is called.
Usage
chisq.test(x, ...)
# S3 method for default
chisq.test(x, ...)
# S3 method for fisher
chisq.test(x, ...)
Arguments
x
Either the output of the agg_index function with
method = "fisher" as parameter, or another R object. In the latter
case, stats::chisq.test is called.
...
Further arguments to be passed to
stats::chisq.test.
Details
Under the null hypothesis for Fisher's aggregation index (index = 1, i.e. a
random pattern is observed), (N - 1)*index follows a chi-squared distribution
with N - 1 degrees of freedom. N is the number of sampling units.
References
For count and incidence data:
Madden LV, Hughes G. 1995. Plant disease incidence: Distributions,
heterogeneity, and temporal analysis. Annual Review of Phytopathology 33(1):
529<U+2013>564.
doi:10.1146/annurev.py.33.090195.002525
Patil GP, Stiteler WM. 1973. Concepts of aggregation and their
quantification: a critical review with some new results and applications.
Researches on Population Ecology, 15(1): 238-254.