youden {spatstat.explore}R Documentation

Youden Statistic

Description

Calculate the Youden statistic for an ROC curve.

Usage

youden(X, sign = c("positive", "absolute", "negative"))

Arguments

X

ROC curve (object of class "roc" produced by roc).

sign

Character string indicating which version of the statistic to calculate.

Details

For a receiver operating characteristic (ROC) curve, the Youden statistic is the maximum vertical deviation between the curve and the diagonal line y=x.

Suppose R(p) denotes the ROC curve as a function of the horizontal coordinate p. If sign="positive" (the default), deviation is defined as the positive part \max(0, R(p)-p). If sign="absolute", deviation is defined as the absolute value | R(p) - p|. If sign="negative", deviation is defined as the negative part \max(0, p - R(p)). The maximum deviation over all values of p is determined. The result is always nonnegative.

Value

Numeric value or vector, containing nonnegative values.

Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au.

References

Youden, W.J. (1950) Index for rating diagnostic tests. Cancer 3, 32–35.

See Also

roc, auc

Examples

  a <- with(split(mucosa), roc(ECL, "y", baseline=other, high=FALSE))
  youden(a)

[Package spatstat.explore version 3.5-2 Index]