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Package 'limma' - Bioconductor

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24 auROC<br />

auROC<br />

Area Under Receiver Operating Curve<br />

Description<br />

Compute exact area under the ROC for empirical data.<br />

Usage<br />

auROC(truth, stat=NULL)<br />

Arguments<br />

truth<br />

stat<br />

logical vector, or numeric vector of 0s and 1s, indicating whether each case is a<br />

true positive.<br />

numeric vector containing test statistics used to rank cases, from largest to smallest.<br />

If NULL, then truth is assumed to be already sorted in decreasing test statistic<br />

order.<br />

Details<br />

A receiver operating curve (ROC) is a plot of sensitivity (true positive rate) versus error (false<br />

positive rate) for a statistical test or binary classifier. The area under the ROC is a well accepted<br />

measure of test performance. It is equivalent to the probability that a randomly chosen pair of cases<br />

is corrected ranked.<br />

Here we consider a test statistic stat, with larger values being more significant, and a vector truth<br />

indicating whether the null hypothesis is in fact true. Correct ranking here means that truth[i] is<br />

greater than or equal to truth[j] when stat[i] is greater than stat[j]. The function computes<br />

the exact area under the empirical ROC curve defined by truth when ordered by stat.<br />

Value<br />

Numeric vector giving area under the curve, 1 being perfect and 0 being the minimum, or NULL if<br />

truth has zero length.<br />

Author(s)<br />

Gordon Smyth<br />

See Also<br />

See 08.Tests for other functions for testing and processing p-values.

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