Consider the following table Following is the graphic repres

Consider the following table.

Following is the graphic representation of the table above, using six side-by-side dotplots. The mean commute time for each city has been visually estimated and located with an X.

(a) Does it appear that the city has an effect on the average amount of time spent by workers who commute to work during the 8:00 AM rush hour? Explain.

(b) Does it visually appear that the city has an effect on the variation in the amount of time spent by workers who commute to work during the 8:00 AM rush hour? Explain.

Solution

A.

No. The X marks are pretty close to each other, as we can see. Atlanta is a little far, but it\'s not very far. So no, it doesn\'t appear that the city has an effect on the average amount of time.

B.

Yes. Visually, we can see that the spread of values are pretty much different for Atlanta and St. Louis, for example. Atlanta has a much smaller range than St. Louis.

Thus, visually, the city has an effect on the variation.