Question

Use MegaStat, MINITAB, or another software package to perform Tukey’s test for significant pairwise differences. Perform the test using both the 5 percent and 1 percent levels of significance.

Sales of People magazine are compared over a 5-week period at four Borders outlets in Chicago.

Weekly Sales
Store 1	Store 2	Store 3	Store 4
99	97	90	103
108	79	91	117
105	82	74	87
114	82	108	101
112	101	93	98

(a) Calculate the mean for each group and the Tukey test statistic T_calc for each pair. Provide the critical values for both α = .05 and α = .01. (Input the mean values within the input boxes of the first row and input boxes of the first column. Input T_calc in the appropriate boxes in the table. Round all answers to two decimal places.)

Post hoc analysis:

Tukey simultaneous comparison t-values (d.f. = 16)
		Store 2	Store 3	Store 4	Store 1
Store 2
Store 3
Store 4
Store 1
Critical values for experimentwise error rate:
		0.05
		0.01

(b) Use Tukey simultaneous comparison t-values and choose the correct answer.

• The weekly sales of Store 1 and Store 2 differ.

• The weekly sales of Store 3 and Store 4 differ.

(c) The Tukey test is used for simultaneously comparing means because it offers good power and maintains the desired overall probability of Type I error.

• True

• False

Answer 1

from Mega stat:

a)

Tukey simultaneous comparison t-values (d.f. = 16)
		Store 2	Store 3	Store 4	Store 1
		88.2	91.2	101.2	107.6
Store 2	88.2
Store 3	91.2	0.48
Store 4	101.2	2.06	1.59
Store 1	107.6	3.08	2.60	1.01

critical values for experimentwise error rate:
		0.05	2.86
		0.01	3.67

b)

The weekly sales of Store 1 and Store 2 differ.

c)

True