studpermu.test

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Studentised Permutation Test

Perform a studentised permutation test for a difference between groups of point patterns.

Keywords
htest, spatial
Usage
studpermu.test(X, formula, summaryfunction = Kest,
       ..., rinterval = NULL, nperm = 999,
        use.Tbar = FALSE, minpoints = 20, rsteps = 128,
        r = NULL, arguments.in.data = FALSE)
Arguments
X
Data. Either a hyperframe or a list of lists of point patterns.
formula
Formula describing the grouping, when X is a hyperframe. The left side of the formula identifies which column of X contains the point patterns. The right side identifies the grouping factor. If the formula is mis
summaryfunction
Summary function applicable to point patterns.
...
Additional arguments passed to summaryfunction.
rinterval
Interval of distance values $r$ over which the summary function should be evaluated and over which the test statistic will be integrated. If NULL, the default range of the summary statistic is used (taking the intersection of
nperm
Number of random permutations for the test.
use.Tbar
Logical value indicating choice of test statistic. If TRUE, use the alternative test statistic, which is appropriate for summary functions with roughly constant variance, such as $K(r)/r$ or $L(r)$.
minpoints
Minimum permissible number of points in a point pattern for inclusion in the test calculation.
rsteps
Number of discretisation steps in the rinterval.
r
Optional vector of distance values as the argument for summaryfunction. Should not usually be given. There is a sensible default.
arguments.in.data
Logical. If TRUE, individual extra arguments to summaryfunction will be taken from X (which must be a hyperframe). This assumes that the first argument of summaryfunction is the point pa
Details

This function performs the studentized permutation test of Hahn (2012) for a difference between groups of point patterns.

The first argument X should be either [object Object],[object Object] A group needs to contain at least two point patterns with at least minpoints points in each pattern.

The function returns an object of class "htest" and "studpermutest" that can be printed and plotted. The printout shows the test result and $p$-value. The plot shows the summary functions for the groups (and the group means if requested).

Value

  • Object of class "studpermutest".

References

Hahn, U. (2012) A studentized permutation test for the comparison of spatial point patterns. Journal of the American Statistical Association 107 (498), 754--764.

Aliases
  • studpermu.test
Examples
testpyramidal <- studpermu.test(pyramidal, Neurons ~ group)
Documentation reproduced from package spatstat, version 1.42-2, License: GPL (>= 2)

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