The records of 27 farm operators participating in farm business analysis programs in 5 Ohio schools were studied to develop and test a model for determining the influence of the farm business analysis phase of vocational agriculture instruction in farm management. Economic returns were measured as ratios between 1965 program inputs and outputs determined by change in net farm income between 1964 and 1965. Data collected included: (1) the relative change in understanding of profit maximizing economic principles indicated by the change in test scores, (2) the change in farm income indicated by selected economic efficiency factors, (3) the association between understanding of principles and the economic efficiency of farm operators, and (4) the ratio between input cost of instruction and economic returns expressed as net farm income. In pilot trial the test group showed: (1) an improved mean change in test scores, (2) increased volume and economic efficiency in the farm business, (3) a positive association between farm operators' understanding of profit maximizing economic principles and changes in their economic efficiency, and (4) a $53.16 increase in net farm income for each $1.00 expended by farmers on instruction. Refinement of the model procedure was projected as a means of advancing inquiry into the micro-economic assessment of investments in agricultural education. (DM)