This data comes from a pilot experiment, which fired a sequence of 10 shots through a set of six paper targets that were equally spaced from 3 ft to 18 ft and recorded the size of the pellet pattern at 18 ft. They then repeated the experiment with five of the targets removed and a single target at 18 ft. The third variable indicate with and without intermediate targets.
data(jauhari1.df)M. Jauhari, S. M. Chatterjee, and P. K. Ghosh. Statistical treatment of pellet dispersion data for estimating range of firing. Journal of Forensic Sciences, 17(1):141-149, 1972.