Predicition - a statistically significant validity coefficient is helpful in showing that for a group of persons a test is related to job success. However, the coefficient itself does not help us in prediciting the job success of individuals. Yet the predicition of an individuals likelihood of job success is preciselly what an employment manager wants. For individual prediction purposes, we can turn to the use of linear regression and expectancy charts to aid us in selection decision making. These should be develop only for those predictors that have proven to have a statistically significant relationship with the criterion.
In using these mehtos, a practitioner is simply taking predictor information, such as test scores, and predicting an individual's job success, such as rated job performance, from this information. For each metho, one key assumption is that we are utilizing information collected on a past or present group of employees and making predictions for a future group of employees.