Lee Joseph Cronbach

Lee Joseph Cronbach was a pioneer of new testing methods and measurement systems in the field of psychology, including Cronbach’s alpha, generalizability theory, and instruction and program evaluation.

Cronbach’s alpha (also known as the coefficient alpha) is a measurement tool. The coefficient alpha is useful because it demonstrates the relationship of a set of items. The alpha determines how a set of items are closely tied together and measure of scale of reliability. This alpha helps researchers determine if the tests they use are measuring what they set out to measure and if the questions on the test are related well to this goal and to each other. It typically is used with Likert scale tests. The formula of his alpha was simple so many researchers could utilize the formula to identify consistency of their set of data, especially since it was developed before computers were common place.

The Generalizability Theory helped to provide a comprehensive framework to identify possible sources of measurement error. Before Generalizability Theory, test reliability was analyzed using classical test theory, which could only measure the possibility of an error for one factor.

Cronbach realized that multiple factors could influence a respondent’s consistency. For example, if the same test proceeds twice, respondents could answer the test similarly due to their memory, not due to their consistency. So, Cronbach and his colleague Goldine Glesser produced the Generalizability theory, which can identify measurement errors from multiple factors in a single test.

Cronbach also changed instruction and evaluation programming. Before he came up with new methods of evaluation, he criticized how evaluations and tests were viewed as detached, objective scientific activities to measure how well a person learned. To provide better feedback for students’ accomplishments, Cronbach believed that it is important to find students’ aptitudes and understand which learning environment best fits their skills. He developed personnel decision theory with Goldine Glesser to help people find their strengths and where they could best be applied. He also worked with Richard Snow to develop ideas on finding the right learning environment for people.

Cronbach was born on April 22, 1916 and died on October 1, 2001 in Fresno, California. From 1946 to 1948, he served as an associate professor at the University of Chicago. Lee was a professor from 1948 to 1964 at the University of Illinois at Urbana Champaign. From 1964 to 1965, after his professor years at the University of Illinois, he was the president of the American Psychological Association. He finished his career at Stanford as a professor from 1964 to 1980.

His work with measurement tools were innovative and effective. His book about psychological testing called Essentials of Psychological Testing has 155 published editions between 1949 to 1998 in 4 languages. In 2002, he was nominated as an eminent psychologist of the 20^th century by the American Psychological Association.