Q.4.162 - Elementary Statistics

Question

Gas Gurzlers. The data for gas mileage and engine displacement for $121$ vehicles from Exercise 4.78 are provided on the WeissStats site.

a. decide whether the use of the linear correlation coefficient as a descriptive measure for the data is appropriate. If so, then also do parts (b) and (c).

b. obtain the linear correlation coefficient.

c. interpret the value of r in terms of the linear relationship between the mo variables in question.

Step-by-Step Solution

Answer

The concave upward curving pattern may be seen in the data. As a result, there is no linear trend in the data. So, portions (b) through (c) will be omitted.

Part (a) Step 1: Given Information

The data for gas mileage and engine displacement for $121$ vehicles from Exercise 4.78 are provided on the WeissStats site.

Part (a) Step 2: Explanation

The MINITAB: can be used to create a scatterplot for the given data.

Step 1: Select Graph > Scatterplot from the drop-down menu.

Step 2: Click OK after selecting With Connect Line.

Step 3: Add an MPG column to the $Y$ variables section.

Step 4: Add a Disp column to the $X$ variables section.

Step 5: Click the OK button.

The resulting scatterplot will be

Finding a regression line for the data is not acceptable since the observations are not dispersed around a line in the scatterplot above.