lrpost

Posterior probability from a likelihood ratio

R

lrpost(lr, prior)

Python

crimlab.lrpost(lr, prior)

Command line

crimlab lrpost --lr VALUE --prior VALUE

Turns a likelihood ratio into the probability of the first hypothesis, which needs a prior. A large ratio with a small prior can still leave that probability low; reading the ratio as the probability is the prosecutor’s fallacy. See proof("lrpost").

Parameters

lr

Likelihood ratios: positive numbers.

prior

The prior probability of the first hypothesis, strictly between 0 and 1: one value, or one per ratio, matched to lr by name when both are named with unique names.

Returns

The posterior probabilities.

Examples

lrpost(lr = 1e6, prior = 1 / 5e6)

Generated from the R help page: lrpost in the R reference.