Yield variability can be significantly higher at the farm level than at more aggregated levels, including the county. However, due to a dearth of available farm level data, much stochastic analysis involving farm yields utilizes more aggregated yield data as a proxy for the farm level. We empirically evaluate farm-level variability using longitudinal farm level data sets available from the Kansas Farm Management Association and the Illinois Farm Business and Farm Management Association. For corn, soybeans, and wheat, we compare the farm level yield variability obtained from this data to that inferred from Federal crop insurance premiums. The farm management data exhibit lower yield variability than are implied by the crop insurance premiums.