Chapter 4.2, Problem 4.45E

(a)

To determine

To explain that do the plot and regression generally support the hypothesis that mortality is lower at hospitals that treat more heart attacks and also is the relationship very strong.

Explanation of Solution

Yes it supports because the scatterplot (plus the regression line) slope downwards. This relationship does not seem very strong, because the regression line is not very steep.

(b)

To determine

To find out in what way is the pattern of the plot nonlinear and also does the nonlinearity strengthen or weaken the conclusion that heart attack patients should avoid hospitals that treat heart attacks and why.

Explanation of Solution

The pattern is nonlinear because for a very low number of patients treated, we note that the mortality is very high (and thus deviated strongly from the regression line).

This strengthens the conclusion that heart attack patients should avoid hospitals that treat few heart attacks, because the mortality rate in general is a lot higher in these hospitals.