A study analyzed the contributions of education to U.S. economic growth during the years 1948 to 1973. By allocating the growth of the quality of labor input among the contributions of changes in the composition of the labor force by sex, age, education, employment status, and occupation, researchers were able to separate the contribution of education to economic growth from the contributions of other changes in the composition of the labor force. They concluded that investment in education is very large by comparison with labor market input, amounting to 5.13 times labor input in 1973. The rate of growth for investment is twice as high as that of labor input. Investment is highest for elementary education, next to highest for secondary education, and lowest for higher education. Another finding of the study is that while the value of investment per student in constant price rises for males and females with elementary and secondary education, this value peaked for college trained males in 1955 and for college trained females in 1950. (This study is one in a series on the relationship between education and productivity.) (MN)