One of the important and relatively unique contributions of the MCMI has been the development and availability of data on its diagnostic efficiency. This is usually calculated by designating BR scale scores of 75 and/or 85 as test positives and comparing these with clinician ratings of whether the characteristics predicted by the scale scores actually matched these clinician ratings. In some settings, however, it is important to take into account the frequency by which a disorder occurs in that setting (BR of the disorder). For a test to be effective, it must diagnose a disorder more accurately than the chance occurrence as determined by the BR. For example, forensic and/or substance abuse treatment facilities usually have high numbers of persons with antisocial personality styles. In these cases, calculation of the positive predictive power of the MCMI for the particular setting is recommended.