Psychometrics and the Importance of Psychological Measurement

W e believe that everyone needs to understand the basic principles of psychological measurement. Whether you wish to be a practitioner of behavioral science, a behavioral researcher, or a sophisticated member of modern society, your life is likely to be affected by psychological measurement. If you are reading this book, then you might be considering a career involving psychological measurement. Some of you might be considering careers in the practice or application of a behavioral science. Whether you are a clinical psychologist, a school psychologist, a human resources director, or a teacher, your work might require you to make decisions on the basis of scores obtained from some kind psychological test. When a patient responds to a psychopathology assessment, when a student completes a test of cognitive ability, or when a job applicant fills out a personality inventory, there is an attempt to measure some type of psychological characteristic. In such cases, basic measurement information needs to be examined carefully if it is used to make decisions about the lives of people. Without a solid understanding of basic principles in psychological measurement, test users risk misinterpreting or misusing information derived from psychological tests. Such misinterpretation or misuse might harm patients, students, clients, employees, and applicants, and it can lead to lawsuits for the test user. Proper test interpretation and use can be extremely valuable for test users and beneficial for test takers.