The methodology of five national surveys designed to estimate the scale and scope of training was analyzed to identify the reasons underlying the variability and unreliability of estimates of education and training. The five surveys were as follows: May Triennial Adult Education Supplement to the Current Population Survey, National Longitudinal Survey of Youth, Survey of Income and Program Participation, National Longitudinal Survey of High School Class of 1972, and High School and Beyond. The analysis focused on the following: fundamental purpose of each survey, population sampled, goodness of fit, and survey structure/design. The analysis established that the five surveys do not measure fully what they purport to measure. It was concluded, however, that when taken collectively, they provided an invaluable insight into the nature of work-related education and training in the United States. The following are recommendations for improving the surveys' reliability and capacity for measuring the scale and scope of education and training: (1) "bundle" questions focusing on incidence of work-related education and training with questions dealing explicitly with work and the skills needed for it; (2) include matched samples of employment establishments and employees; and (3) develop more explicit questions focusing on training credentials and certificates. (Contains 16 figures/tables and 19 references.) (MN)