Technology is now widely available to vary the rate of crop inputs including seed, liquid or dry fertilizer, pesticides etc. Relative to traditionally applying one average rate across an entire field, these tools allow input rates to be increased in areas where additional economic response may be expected (“missed yield opportunity”) and reduced in areas where average rates may be expected to be well beyond economical (“excess input wasted”).There have been questions regarding the payback of adopting these technologies, as well as how to decide what rate goes where in a field. With the increasing prevalence of yield monitors on combines, it is becoming easier to conduct field trials which can measure the response to inputs in various regions of a field to measure what variability in response exists across a field. Not only can these input response trials help determine the return on investment for variable rating for a given field during a given year, they can also be used to ground-truth recommendations, management zone delineations and sensory technology which may be used in attempts to predict where areas of higher and lower yield response are expected to occur. This project was developed to assess variability in yield response to the most common crop inputs (nitrogen fertilizer, seed) for corn, soybeans and wheat across a large number of fields throughout Ontario.