This report evaluates the benefits of conducting a formal survey, in addition to an informal or rapid reconnaissance survey, in the diagnostic phase of a farming systems research program. The purpose of the survey was to develop an understanding of local farming systems and to plan a program of experiments to address farmers problems. The researchers evaluated the benefits of the formal survey by comparing data collected in an informal survey to data collected in a subsequent formal survey. the researchers found that the contribution of the formal survey was marginal to its costs. According to the rating system outlined in this paper, 87% of the parameter estimates in the informal survey were highly or moderately accurate. The experiments proposed following the informal survey were modified only slightly as a result of new findings from the formal survey. the data thus support the hypothesis that the informal survey is an effective and sufficient method of developing an understanding of farming systems and planning experimental programs for farmers.