Birth weight, exploration. Table 13.3 lists birth weights of infants based on the smoking status of mothers.

(a) Outline this study’s design using a sketch of the type presented in Section 2.2

(see Figure 2.1) to depict this study’s design.

(Comment: In contrast to the pets and stress illustrative example, these data are nonexperimental.)

(b) Figure 13.5 shows side-by-side boxplots of the response variable in the four groups. Interpret this plot.