In Section $2.10,$ we described Data Set BONEDEN.DAT (at www.cengagebrain.com) concerning the effect of tobacco use on BMD.
Suppose we group the twin pairs according to the difference in tobacco use expressed in 10 pack-year groups (0-9.9 pack-years/10-19.9 pack-years/20-29.9 pack-years/30-39.9 pack-years/40+ pack-years). Compute appropriate descriptive statistics, and provide a scatter plot for $\mathrm{C}$ grouped by the difference in tobacco use in pack-years.