A student runs an experiment to study the effect of gas brand and car type on mileage.She uses 3 different brands of gas on 8 different types of cars.
A)Gas brand SS: 3 df; Car type SS: 7 df; SSE: 14 df
B)Gas brand SS: 3 df; Car type SS: 4 df; SSE: 12 df
C)Gas brand SS: 1 df; Car type SS: 7 df; SSE 14 df
D)Gas brand SS: 2 df; Car type SS: 3 df; SSE: 8 df
E)Gas brand SS: 2 df; Car type SS: 7 df; SSE 14 df

Question

Quizplus · Accepted Answer

The best choice is E because it has a balanced number of degrees of freedom for both gas brand and car type, with enough error degrees of freedom to estimate the variability within each combination of gas brand and car type. This will allow for a more accurate analysis of the effects of both factors on mileage. Additionally, using 2 gas brands instead of 3 reduces the complexity of the experiment without sacrificing the ability to draw meaningful conclusions.

A Student Runs an Experiment to Study the Effect of Gas