In: Statistics and Probability
A pediatrician wants to determine the relation that exists between a child's height, x, and head circumference, y. She randomly selects 11 children from her practice, measures their heights and head circumferences, and obtains the accompanying data. Complete parts (a) through (g) below.
| Height (inches), x | Head Circumference (inches), y | 
| 28 | 17.7 | 
| 24.25 | 17.3 | 
| 25.5 | 17.2 | 
| 25.75 | 17.7 | 
| 24.5 | 17.0 | 
| 28.25 | 17.8 | 
| 26.75 | 17.5 | 
| 27.25 | 17.5 | 
| 26.75 | 17.5 | 
| 26.75 | 17.7 | 
| 27.5 | 17.7 | 
(a) Find the least-squares regression line treating height as the explanatory variable and head circumference as the response variable.
(b) Interpret the slope and y-intercept, if appropriate.
(c) Use the regression equation to predict the head circumference of a child who is
24.5 inches tall.
(d) Compute the residual based on the observed head circumference of the 24 .5 -inch-tall child in the table. Is the head circumference of this child above or below the value predicted by the regression model?
(e) Draw the least-squares regression line on the scatter diagram of the data and label the residual from part (d).
(f) Notice that two children are 26.75 inches tall. One has a head circumference of 17.5 inches; the other has a head circumference of 17.7 inches. How can this be?
(g) Would it be reasonable to use the least-squares regression line to predict the head circumference of a child who was 32 inches tall? Why?