Question

For a project in his statistics class, Mark conducted a survey in which he asked participants to assign status ratings to three photographs of cars (Corvette, Toyota RAV4, Honda Civic) on a scale of 1 to 10. The average ratings were: (a) Corvette 8.3; (b) RAV4 6.7; (c) Civic 3.9). On the basis of t-tests, he concluded that all of the differences among the three mean ratings were statistically significant. He was disappointed to learn that he received a low grade on the project due to the fact that he had used the wrong statistical test. Explain why Mark's approach to analyzing his data was incorrect. State which statistical test he should have used and explain why

Answer 1

Answer:
Mark should have used One Way ANOVA test instead of pairwise t tests.

Explanation:

When there are more than 2 treatments, such as in this case: status ratings to three photographs of cars (Corvette, Toyota RAV4, Honda Civic) on a scale of 1 to 10. ANOVA is required because of the effect of Type I Error as follows. In the case of repeated t tests, the more hypothesis tests we use, the more we risk of making a Type I Error and less Statistical Power a test has, whereas ANOVA controls Type I Error.