Evaluation of models predicting winter wheat yield as a function of winter wheat and jointed goatgrass densities

Abstract

Abstract Three models that empirically predict crop yield from crop and weed density were evaluated for their fit to 30 data sets from multistate, multiyear winter wheat–jointed goatgrass interference experiments. The purpose of the evaluation was to identify which model would generally perform best for the prediction of yield (damage function) in a bioeconomic model and which model would best fulfill criteria for hypothesis testing with limited amounts of data. Seven criteria were used to assess the fit of the models to the data. Overall, Model 2, provided the best statistical description of the data. Model 2, regressions were most often statistically significant, as indicated by approximate F tests, explained the largest proportion of total variation about the mean, gave the smallest residual sum of squares, and returned residuals with random distribution more often than Models 1, and 3,. Model 2, performed less well based on the remaining criteria. Model 3, outperformed Models 1, and 2, in the number o...