Numerous studies referred to in this book and in other publications have examined the relationship between a proximal sensor, or remote sensing with crop yield and other attributes of interest to precision agriculture. Combining data from two or more sensors tends to increase the relationship between sensor readings and crop attributes. Crop canopy height, active-optical sensor readings, remote sensing data, and weather data have been combined to increase predictability of crop attributes. The fusion of these data requires the use of appropriate statistical tools. Description of several of these tools is provided in this chapter.