In terms of simple correlations, the PCL-R manual states an average score of 22.1 has been found in North American prisoner samples, and that 20.5% scored 30 or higher. An analysis of prisoner samples from outside North America found a somewhat lower average value of 17.5. Studies have found that psychopathy scores correlated with repeated imprisonment, detention in higher security, disciplinary infractions, and substance misuse.[35][36]