PREDICTIVE EFFICIENCY AS A FUNCTION OF AMOUNT OF INFORMATION

The effect of changing the amount of information on judges' predictive efficiency in a clinical prediction task was studied. Thirty judges predicted 30 students' average achievement scores on the basis of different amount of test data. One group of judges had information about the intercorrelations among the tests and the ecologkal validity of the tests. Another group of judges had only informahion about which tests were used. The predictive efficiency was not a monotonically increasing function of amount of test data. The most marked result was that the relative predictive efficiency decreased from four to six tests in both groups.