Valid measures of the changing output of the marketing system in comparison with the inputs of resources such as labor are of basic importance in appraising the efficiency of the marketing system, in determining those segments of the system where possibilities for improvement are marked, and in examining a wide variety of other economic questions. Attempts to improve measures of input-output relationships have been beset by numerous difficulties relating to the quality of output, the fact that some output is in the form of service attached to a product rather than a physical commodity, the problems of disassociating inputs of different types of factors, and other questions regarding the nature of inputs. This article reports various methods that can be employed in the measurement of output per unit of labor and suggests the difference or bias that can result when various concepts are used. The methods employed produce findings that give a picture of trends in output per unit of labor input. As further Departmental studies yield improved measures of these relationships, they will be reported.