Computes the InterModel Vigorish ('IMV'), a metric for comparing the predictive accuracy of two models for binary outcomes. The IMV is derived from the expected value of a bettor using one model's predicted probabilities against those of a competing model, and is estimated via k-fold cross-validation. Methods are provided for generalized linear models, mixed-effects models ('lme4'), and item response theory models ('mirt'). See <doi:10.1371/journal.pone.0316491>.