As you drive down the road in early summer, most corn fields appear uniform. However, a closer examination often reveals a wide variation in how evenly plants are spaced within the row. When planters are not operated or functioning properly, a high number of doubles or gaps may occur. Some researchers have suggested using standard deviation (SD) as a measure of in-row corn stand uniformity (Nielson, 1991). At Purdue University, Nielson (1991) has suggested that corn grain yield declines about 2.5 bu/acre for each 1 inch increase in standard deviation above a value of 2 inches. Conversely, many researchers have seen very little impact of corn spacing SD on final grain yield (Butzen, 1998). Nafziger (1996) has suggested that SD alone is not a good means of predicting yield responses to stand variability because of the differing and interactive effects of row skips, doubles, and plant density.