Learning Objectives

After completing your study of this chapter, you should be able to do the following:

• Identify evidence of validity of a test based on its relationships to external criteria, and describe two methods for obtaining this evidence.
• Read and interpret validity studies.
• Discuss how restriction of range occurs and its consequences.
• Describe the differences between evidence of validity based on test content and evi­dence based on relationships with external criteria.
• Describe the difference between reliability/precision and validity.
• Define and give examples of objective and subjective criteria, and explain why crite­ria must be reliable and valid.
• Interpret a validity coefficient, calculate the coefficient of determination, and con­duct a test of significance for a validity coefficient.
• Explain the concept of regression, calculate and interpret a linear regression formula, and interpret a multiple regression formula.

Chapter Summary

Evidence of validity based on test–criteria relations—the extent to which a test is related to independent behavior or events—is one of the major methods for obtaining evidence of test validity. The usual method for demonstrating this evidence is to correlate scores on the test with a measure of the behavior we wish to predict. This measure of independent behavior or performance is called the criterion.

Evidence of validity based on test–criteria relations depends on evidence that the scores on the test correlate significantly with an independent criterion—a standard used to measure some characteristic of an individual, such as a person’s performance, attitude, or motivation. Criteria may be objective or sub­jective, but they must be reliable and valid. There are two methods for demonstrating evidence of validity based on test–criteria relations: predictive and concurrent.

We use correlation to describe the relationship between a psychological test and a criterion. In this case, the correlation coefficient is referred to as the validity coefficient. Psychologists interpret validity coefficients using tests of significance and the coefficient of determination.

Either a linear regression equation or a multiple regression equation can be used to predict criterion scores from test scores. Predictions of success or failure on the criterion enable test users to use test scores for making decisions about hiring.

Finally, decisions based on test predictions have far-reaching consequences. Researchers, test develop­ers, test publishers, and test users are ethically and morally responsible for ascertaining that any psycho­logical test used for making predictions and decisions shows acceptable evidence of reliability/precision and validity. Their responsibility also extends to guarding against test misuse and to increasing public awareness about the important role that tests play in test takers’ lives.