Refer to the American Business Review (Jan. 2002) comparison of large-cap, medium-cap, and small-cap mutual funds, Exercise 9.26 (p. 509). Using an experiment-wise error rate of .05, Tukey confidence intervals for the difference between mean rates of return for all possible pairs of fund types are given below.
Comparison Tukey Confidence Interval
µLarge - µMedium..................................... (-.1847, 5.3807)
µLarge - µSmall..................................... (2.4426, 8.0080)
µMedium - µSmall..................................... (-.1554, 5.4100)
a. Why is the Tukey multiple comparisons method preferred over another method?
b. Is there a significant difference between the treatment means for large-cap and medium-cap mutual funds? Explain.
c. Is there a significant difference between the treatment means for large-cap and small-cap mutual funds? Explain.
d. Is there a significant difference between the treatment means for medium-cap and small-cap mutual funds? Explain.
e. Use your answers to parts b-d to rank the treatment means.
f. Give a measure of reliability for the inference in part e.