A meta-analysis conducted in the United Kingdom (Bertua, Anderson & Salgado, 2005) has found that intelligence tests and tests of specific cognitive abilities are strong, reliable and valid predictors of both job performance and response to training. Operational validities are in the range of .5-.6, meaning that these cognitive tests can account for approximately 30% of the variance in job performance between candidates. This makes cognitive ability tests the single strongest predictor of job performance, over and above other popular measures such as personality assessments and job interviews. The predictive validity of cognitive ability tests generalises across job types and settings, meaning that these tests are useful predictors of most jobs in most industries (if not all!). Their ability to predict job performance is strongest for more complex roles, such as professional and managerial roles.