kd: Difference of estimated K functions

In smacpod: Statistical Methods for the Analysis of Case-Control Point Data

Difference of estimated K functions

Description

kd determines the difference in estimated K functions for a set of cases and controls.

Usage

kd(
  x,
  case = 2,
  r = NULL,
  rmax = NULL,
  breaks = NULL,
  correction = c("border", "isotropic", "Ripley", "translate"),
  nlarge = 3000,
  domain = NULL,
  var.approx = FALSE,
  ratio = FALSE
)

Arguments

x	A ppp object with marks for the case and control groups.
case	The name of the desired "case" group in levels(x$marks). Alternatively, the position of the name of the "case" group in levels(x$marks). Since we don't know the group names, the default is 2, the second position of levels(x$marks). x$marks is assumed to be a factor. Automatic conversion is attempted if it is not.
r	Optional. Vector of values for the argument r at which K(r) should be evaluated. Users are advised not to specify this argument; there is a sensible default. If necessary, specify rmax.
rmax	Optional. Maximum desired value of the argument r.
breaks	This argument is for internal use only.
correction	Optional. A character vector containing any selection of the options "none", "border", "bord.modif", "isotropic", "Ripley", "translate", "translation", "rigid", "none", "periodic", "good" or "best". It specifies the edge correction(s) to be applied. Alternatively correction="all" selects all options.
nlarge	Optional. Efficiency threshold. If the number of points exceeds nlarge, then only the border correction will be computed (by default), using a fast algorithm.
domain	Optional. Calculations will be restricted to this subset of the window. See Details of Kest.
var.approx	Logical. If TRUE, the approximate variance of \hat K(r) under CSR will also be computed.
ratio	Logical. If TRUE, the numerator and denominator of each edge-corrected estimate will also be saved, for use in analysing replicated point patterns.

Details

This function relies internally on the Kest and eval.fv. The arguments are essentially the same as the Kest function, and the user is referred there for more details about the various arguments.

Value

Returns an fv object. See documentation for Kest.

Author(s)

Joshua French

References

Waller, L.A. and Gotway, C.A. (2005). Applied Spatial Statistics for Public Health Data. Hoboken, NJ: Wiley.

See Also

Kest, eval.fv

Examples

data(grave)
kd = kd(grave)
plot(kd)

smacpod documentation built on Oct. 31, 2024, 1:08 a.m.