Book excerpt: This memoir is the eighth in a series related to Mathematical Models of Crop Growth and Yield. The series focuses on ideas which have been found useful in describing crop response to applied nutrients (N, P, and K) and accumulation of biomass and mineral elements with calendar time. No attempt has been made to survey the broad field of crop modeling. Results have evolved out of work with farmers and engineers over a period of nearly forty years. There has been extensive collaboration with other scientists in Florida as well as other regions within the USA. Analysis has been drawn from the large array of data from research conducted around the world over 150 years. While basic concepts from physics, chemistry, and biology have been incorporated, the models have been developed at the field scale for the sake of application. Methods of applied malthematics and statistics have been utilized to provide a more rigorous foundation to the models. Procedures from regression and analysis of variance have been borrowed from statistics. In fact this is the focus of the present memoir. As often occurs in research, the question is how to analyze a complex set of data. For example, response of biomass and mineral uptake to applied nutrients (N, P, and K) where some other management factor (such as intercropping) is varied as well. Is it appropriate to average over the response variables? Are there some parameters in the model which are common among different management factors? One can make such judgments based either on visual inspection of data or on statistical analysis. The goal is to simplify the analysis as much as can be justified. Throughout this analysis analytical functions have been used, in contrast to numerical procedures. A particular set of data for response of corn (Zea mays L.) to applied N, P, and K is used to illustrate the analytical procedures. The extended logistic model describes the data rather well. Coupling of biomass yield and plant N uptake is achieved with a hyperbolic phase relation. The memoir contains 36 pages, including 19 references, 21 tables, and 11 figures.