Exercise 9.3 presents a regression model for predicting the average birth weight of babies based on length of gestation, parity, height, weight, and smoking status of the mother. Determine if the model assumptions are met using the plots below. If not, describe how to proceed with the analysis.

Data from Exercise 9.3

We considered the variables smoke and parity, one at a time, in modeling birth weights of babies in Exercises 9.1 and 9.2. A more realistic approach to modeling infant weights is to consider all possibly related variables at once. Other variables of interest include length of pregnancy in days (gestation), mother's age in years (age), mother's height in inches (height), and mother's pregnancy weight in pounds (weight). Below are three observations from this data set.

The summary table below shows the results of a regression model for predicting the average birth weight of babies based on all of the variables included in the data set.

Residuals 300 250- 200- 150- 100- 50- 0 -60 -40 -20 6 40- O -40- Residuals 20 40 60 400 800 Order of collection 1200 Residuals Residuals 40- -40- 40- 0 -40- 150 80 120 Fitted values 200 250 300 Length of gestation 160 350