Agricultural economists use econometric methods to analyze farm surveys or experimental data to assess the contribution to yield or net profit of various technologies such as Bt seed, insecticides and other factors, but tend not to question whether the technology is needed in the first place. Such analyses and data are often situation dependent, may provide assessment of the static productivity of the factors examined but are less suitable for capturing the interaction between control decisions and dynamic ecosystem reactions, the methods reflect the influence of institutional settings, reflect the context in which the data were collected, and tell of little about the origins of the problem being evaluated, or alternatives to the current production system. Bio-economic analyses use rich biological models as the production function to address many of the deficiencies of econometric methods, and have been applied to the analysis of pesticide use and biotechnology in agriculture. Many of these studies are done as cooperative efforts with scientists from collaborating research institutions.