tippet.plot: Draw a Tippet plot for a forensic comparison system

In davidavdav/ROC: Compute structures to compute ROC and DET plots and metrics for 2-class classifiers.

Draw a Tippet plot for a forensic comparison system

Description

This function draws a Tippet plot for a forensic comparison system, given data in a cst type data frame. Tippet plots are used in the forensic science literature, although the present author does not believe they are very insightful.

Usage

tippet.plot(x, ...)

Arguments

x	An object of class roc, or a data frame that can be coerced to that by using roc(x
...	Further arguments to plot and lines

Details

A tippet plot shows both the true positive and the true negative rate as a function of score threshold. The x-axis is shown on a logarithmic scale, with the title "LR bigger than" indicating the cumulative nature of the y-axis.

The Tippet plot shows the same basic information as a ROC or DET plot, but explicitly shows the score axis, which is deemed a Likelihood Ratio. However, it is very hard to evaluate if the LR distribution has the correct properties. For a Tippet plot, for instance, the slopes at log LR = 0 for the two curves should be the same for well calibrated LRs.

Author(s)

David A. van Leeuwen

Examples

## data from TNO's submission to NIST Speaker Recogntion Evaluation 2008
data(tno.2008)
tippet.plot(tno.2008)

davidavdav/ROC documentation built on Sept. 8, 2023, 2:39 p.m.