Edward Kellogg Strong, Jr., born in 1884 in Syracuse, New York, was the first author of the Strong Interest Inventory (Strong). At the age of 40, Strong took a position in the School of Business at Stanford University where he began his research in interest measurement. He remained at Stanford until his retirement in 1949. After his retirement, Strong continued his work in interest measurement in collaboration with his son-in-law, Ralph F. Berdie, who was a professor at the University of Minnesota, and with other Minnesota faculty including Donald G. Paterson, John G. Darley, David P. Campbell, Theda Hagenah, Wilbur L. Layton, Edmund G. Williamson, and Kenneth E. Clark. After Strong’s death in 1963, the University of Minnesota established the Center for Interest Measurement Research, now directed by Jo-Ida C. Hansen, and all of Strong’s data were moved from Stanford to Minnesota. The most recent revision of the Strong was published in 2004, making it the longest continuously published interest inventory. The longevity of the Strong, which still uses Strong’s method of empirical contrast groups to construct occupational scales, is due in large part to the early work of Strong who laid the empirical foundation for the inventory.
Before Interest Measurement
Strong lived in many parts of the United States during his lifetime. His father was a minister, and when Strong was a child they moved to the Midwest (Bloomington, Illinois, and Bay City, Michigan) where he developed a love for the outdoors. In 1902, the family moved to San Francisco, and Strong attended the University of California, Berkeley where he majored in biology. After college, Strong spent a year with the U.S. Forestry Service. His love for the Sierras and the outdoors was a constant throughout his life, and at the time of his retirement his score on the Strong Nature scale was one of the three highest scores on his profile (the other two were Science and Mathematics). Strong’s daughter described his love for nature in a 1987 interview: “He loved his garden and his golf. He especially loved the mountains, the ocean and the desert. He knew the names of the plants and trees and was continually teaching them to us. He also knew the constellations of stars. He loved to be in the outdoors—to hike, to swim, or to fish” (Hansen, 1987, p. 121).
Strong returned to Berkeley and completed an M.A. in psychology in 1909. He then moved back to the East to attend Columbia University. As a graduate assistant working with Harry L. Hollingworth at Bernard College, Strong met an undergraduate, Margaret Hart, whom he married in 1911, the same year that he completed his Ph.D. Strong remained at Columbia until 1914 when he joined the psychology faculty at George Peabody College for Teachers in Tennessee where he published Introductory Psychology for Teachers. Strong’s early career also focused on research in marketing and advertising. His research in this area resulted in several publications and the book The Psychology of Selling and Advertising published in 1925.
As was the case for many applied psychologists of Strong’s generation, World War I had a direct impact on his career. He entered the military in 1917 and served on the Committee on Classification for Personnel and as a personnel specialist with duty assignments at Camp Taylor, Kentucky, and Camp Kearny, California. Strong’s work with the Committee on Classification led him to appreciate the efficacy of the Army tests for predicting a person’s ability to do a job and to understand the need for career guidance.
After his military service, Strong was on the faculty of the Carnegie Institute of Technology where he participated in a faculty-graduate student proseminar run by Clarence Yoakum, which spawned several attempts by others (e.g., Bruce Moore, J. B. Miner, Max Freyd) to develop instruments to measure vocational interests. When the applied psychology program at Carnegie was dissolved in 1923, Strong moved to Stanford University where he taught courses in business administration, conducted research on the opportunities for Asian Americans in the United States, and eventually was encouraged by his student, Karl Cowdery, to pursue research in interest measurement.
Contributions to Interest Measurement
Strong published the first version of the Strong, the Vocational Interest Blank, in 1927, and from that time forward his research and publications were almost exclusively in test construction and interest measurement. Throughout his time at Stanford, Strong had connections with the faculty at the University of Minnesota where the foundations of vocational guidance and the trait-and-factor theory of counseling were emerging in response to veterans returning to college. Strong became friends with Donald G. Paterson, one of the two founding faculty members of Minnesota’s Department of Psychology (the other was the chair of the department, Richard M. Elliott), through the World War I Committee on Classification. His daughter, Fran Berdie Berninghausen, attended graduate school at Minnesota and later married Ralph Berdie, a faculty member. As a result, Strong occasionally spent summers teaching at the University of Minnesota, visited Minnesota after his retirement to discuss revisions of the Strong, and gave the Walter Bingham Lecture (Satisfaction and Interests) at Minnesota in 1958.
Strong’s first publication on interest measurement, “An Interest Test for Personnel Managers,” appeared in the Journal of Personnel Research in 1926. The first Strong booklet appeared in 1927, and the first manual in 1928. From the start, Strong was interested in the application of interest measurement to career decision making. For example, he wrote in the 1928 manual, “if he [sic] scores high in both law and engineering, he might prepare for both and become a patent attorney, or a lawyer specializing in engineering problems” (p. 2). He also was concerned about evidence of validity for the Strong, acknowledging in the same manual that it will be “some time before the validity of this test can be exactly determined” (p. 2). By 1929 he had published an article that demonstrated the diagnostic value (i.e., predictive validity) of the Strong, and in 1930 he published a test-retest reliability study that spanned 1.5 years. He also worked with Louis L. Thurstone to find a meaningful way to group the scales using a method of constellation analysis that Thurstone had developed.
Strong’s research in interest measurement was a combination of work to revise, improve, and expand his interest inventory and research designed to understand the construct of vocational interests. He published the first women’s version of the Strong in 1935, the first major revision of the men’s form in 1938, and the first major revision of the women’s form in 1946. Additional revisions of the separate-sex Strong, published in 1966 (Men’s Form) and 1969 (Women’s Form), were developed at the University of Minnesota in consultation with Strong.
In addition to the interest inventory manuals and Introductory Psychology for Teachers (1922),The Psychology of Selling Life Insurance (1922), Job Analysis and Curriculum (1923), The Psychology of Selling Advertising (1925), Japanese in California (1933), and Psychological Aspects of Business (1938), Strong published four books on vocational interests. The first, Change of Interests With Age, was published in 1931; Vocational Aptitudes of Second Generation Japanese in the United States appeared in 1933; Vocational Interests of Men and Women in 1943; and Vocational Interests Eighteen Years After College in 1955. These books elaborated on the evidence of reliability and validity for the Strong that Strong himself collected, and the volumes of data presented in each book also provided enormous knowledge about the construct of vocational interests. Vocational Interests of Men and Women was published only 15 years after the first Strong inventory was published, yet it is 746 pages long, contains 197 tables and figures, and reports well over 20,000 numbers (e.g., means, standard deviations, correlations) representing thousands of research participants. This book would be an amazing accomplishment even today with the assistance of high-speed computers to crunch the numbers, but it was a phenomenal accomplishment in 1943 when only about six answer sheets could be scored per hour. The 1955 book was a longitudinal study with Stanford University students.
Strong was described by his daughter Fran as an introverted yet socially skilled person who enjoyed the people with whom he worked but also relished his time alone. His research was supported primarily by scoring fees for tests that people would send to him. His daughter also indicated that he did much of his research at home, where there were no distractions, with the assistance of his two daughters, Fran and Margaret. He often spent the afternoons playing golf or bridge after teaching in the morning and lunching at home. Strong even interjected his interest in golf into his scholarly writing, noting that the correlation of golf scores between the first and second 18 holes in championship play usually is about .30.
John G. Darley, a University of Minnesota faculty member who knew Strong through his summer visits to the Twin Cities of Minneapolis-St. Paul, described him as a grizzly bear who was not hesitant to express his opinions. Darley also reported that Strong himself claimed never to be a theorist but rather a dirty-handed empiricist who even as he worked to develop a theoretical frame for his interest inventory was always ready and eager to go out and collect more data.
- Campbell, D. P. (1971). An informal history of the SVIB. In Handbook for the Strong Vocational Interest Blank (chap. 11). Stanford, CA: Stanford University Press.
- Darley, J. G. (1964). Edward Kellogg Strong, Jr.: 1884-1963. Journal of Applied Psychology, 48, 72-74.
- Hansen, J. C. (1987). Edward Kellogg Strong, Jr.: First author of the Strong Interest Inventory. Journal of Counseling and Development, 66, 119-125.
- Strong, E. K., Jr. (1928). Manual for Vocational Interest Test. Stanford, CA: Stanford University Press.
- Strong, E. K., Jr. (1943). Vocational interests of men and women. Stanford, CA: Stanford University Press.
- Strong, E. K., Jr. (1955). Vocational interests 18 years after college. Minneapolis: University of Minnesota Press.