The data below are from an independent-measures experiment comparing three different treatment conditions regarding attention scores.

Treatment 1 Treatment 2 Treatment 3

0 2 4

0 3 2

0 1 4

3 3 3

0 2 4

0 1 4

1. Explain why an ANOVA should be used instead of a series of t tests to evaluate the mean differences among the three treatment conditions.

2. Use an analysis of variance with = .05 to determine whether these data indicate any significant mean differences among the treatment conditions. Show all your work and the 4 steps of hypothesis testing.

3. Compute ², the percentage of variance accounted for by the treatments.

Using Tukeys HSD procedure, conduct post hoc comparisons of the treatment means, and make a conclusion about which mean(s) is (or are) significantly different.