Lee Joseph Cronbach (April 22, 1916 – October 1, 2001) was an American educational psychologist who made contributions to psychological testing and measurement.
This work of Thurstone intrigued Cronbach, motivating him to complete and receive his doctorate in educational psychology from the University of Chicago in 1940.
These contributions included improvements to the technology of psychometric modeling, as well as reformulations, which went beyond the mathematics of understanding the psychology of test performances.
This allowed Cronbach to lay out guidelines - much like a road-map - for researchers and practitioners of educational psychology spreading awareness of the challenges and prospects of conducting program evaluations.
Beyond that, [Cronbach] shares with the humanistic scholar and the artist in the effort to gain insight into contemporary relationships, and to align the culture's view of man with present realities.
Cronbach had created this formula which could be applied throughout a variety of tests and other measurement instruments - gaining an enormous amount of popularity among practitioners.
The alpha is useful because not only is it easily calculated, but it is also quite general and can be applied universally - for example: dichotomously scored multiple-choice items or polytimous attitude scales.
He began his work with the aim to produce a handbook on measurement - allowing people to apply mathematical concepts to transform one's behaviours and events into quantitative results.
With this in mind, he teamed up with two other members and developed a "random model" (introduced by the British statistician R.A. Fisher) where he was determined to figure out the complexities of error variance.
[4] This "G" theory thus provided a combination of the psychological with the mathematical producing a comprehensive framework and statistical model which identified sources of measurement error.
[11] Cronbach's theory goes beyond examining consistency in a student's relative standing in distribution – it recognizes and acknowledges that the particular item used in any given test is only a small indicator from a wider domain of knowledge.
[11] Cronbach & Meehl believed that "...it [is]imperative that psychologists make a place for [advocating construct validity] in their methodological thinking, so that its rationale, its scientific legitimacy, and its dangers may become explicit and familiar.