TUTORIAL #5 – PRACTICE QUESTIONS (Winter 2014)
1. After conducting anANOVAwith 4 groups and rejecting the null hypothesis, you conduct all possible
pairwise comparisons with multiple t-tests, each with an alpha level of 0.05. Assuming the tests are
independent, what’s the family-wise alpha for this set of comparisons?
Family-WiseAlpha = 0.2649
2. An experiment is conducted to compare the efficiency of 5 treatments for depression: (1) Prozac, (2)
Elavil, (3) Zoloft, (4) Prozac & psychotherapy, and (5) Zoloft plus Psychotherapy.AnANOVAyields a
significant main effect. The experimenter plans (a priori) to conduct the following four comparisons:
i) treatments with psychotherapy vs. treatments without psychotherapy
ii) treatments with Prozac vs. treatments without Prozac
iii) treatments with Zoloft vs. treatments without Zoloft
iv) Prozac with Zoloft (both without psychotherapy) and Elavil
a) What are the coefficients for this linear contrast?
Prozac Elavil Zoloft Prozac & Zoloft &
i) 2 2 2 -3 -3
ii) 3 -2 -2 3