Question

Look at the scatter plot below.

A scatter plot is shown with 20 data points showing a strong negative relationship. The x-values of the data points extend from 0 to 10, and the y-values of the data points extend from 9 to 0.

Which graph shows the best line of fit?

A.
A downward sloping line is drawn on the scatter plot. Most of the data points with x-values less than 4 are above the line, and most of the data points with x-values greater than 4 are below the line.

B.
A downward sloping line is drawn on the scatter plot. Most of the data points are below the line.

C.
A downward sloping line is drawn on the scatter plot. Most of the data points are above the line.

D.
A downward sloping line is drawn on the scatter plot. The number of data points above the line and the number below the line are about equal.

Answer 1

D

A best-fit (regression) line for a scatter with a strong negative relationship should balance the points so there are about as many above the line as below it. Options B and C are clearly biased, and A is skewed by x-value—so D is correct.