# Difference of estimated K functions

### Description

`kd`

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

### Usage

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### Arguments

`x` |
A |

`case` |
The position of the name of the "case" group in levels(x$marks). The default is 2. |

`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. |

`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", "none", "good" or "best". It specifies the edge correction(s) to be applied. |

`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. |

`var.approx` |
Logical. If TRUE, the approximate variance of Kest(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. |

### Value

Returns an `fv`

object. See documentation for `spatstat::Kest`

.

### Author(s)

Joshua French

### References

Waller, L.A. and Gotway, C.A. (2005). Applied Spatial Statistics for Public Health Data. Hoboken, NJ: Wiley. Kulldorff, M. (1997) A spatial scan statistic. Communications in Statistics – Theory and Methods 26, 1481-1496.

### Examples

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