[R] ROC curves using R

[Jonathan Baron]

What is it that you want to compute?  I have a set of
scripts - written by my colleaged David Brainard in
Matlab and translated to R by me - which we used to teach
signal-detection theory in a grad "methods" course.
But they are very straightforward and not worth putting
into a package.  (I'm sure there is something much more
sophisticated one can do, but you don't say what.)

Some useful R functions (illustrated, and probably
self-explanatory):

zHit <- qnorm(Ph)
zFa <- qnorm(Pfa)
dPrime <- zHit-zFa

zCr <- qnorm(1-Pfa)
Beta <- dnorm(zCr,dPrime,1)/dnorm(zCr,0,1)

And here is the optimal "beta" (criterion):

logBetaOpt <- log((pn/ps)*(Vcr + Vfa)/(Vh + Vm))

Jon Baron
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