rocdemo.sca {ROC}R Documentation

function to build objects of class 'rocc'

Description

rocdemo.sca – demonstrate 'rocc' class construction using a scalar marker and simple functional rule

Usage

rocdemo.sca(truth, data, rule, 
       cutpts=NA,
       markerLabel="unnamed marker", caseLabel="unnamed diagnosis")

Arguments

truth true classification of objects. Must take values 0 or 1.
data quantitative markers used to classify
rule rule: a function with arguments (x, thresh) returning 0 or 1
cutpts values of thresholds
markerLabel textual label describing marker
caseLabel textual label describing classification

Details

dxrule.sca is function (x, thresh) ifelse(x > thresh, 1, 0)

The default value of argument cutpts is a point less than min(data), points separating the unique values of data and a point greater than max(data).

Value

an object of S4 class rocc

Note

Author(s)

Vince Carey (stvjc@channing.harvard.edu)

References

See Also

AUC

Examples

set.seed(123)
R1 <- rocdemo.sca( rbinom(40,1,.3), rnorm(40), dxrule.sca,
   caseLabel="new case", markerLabel="demo Marker" )
plot(R1, line=TRUE, show.thresh=TRUE)

truth <- c(0, 1, 0, 1, 1, 0, 1, 1)
data <- c(2, 3, 4, 4, 5, 6, 7, 8)
R2 <- rocdemo.sca(truth, data, dxrule.sca)
plot(R2, line=TRUE, show.thresh=TRUE)
R3 <- rocdemo.sca(truth, data, function(x, thresh) 1 - dxrule.sca(x, thresh))
if (AUC(R2) + AUC(R3) != 1) stop('Sum of AUCs should be 1.')

[Package ROC version 1.4.0 Index]