1. Why does one use a Tukey's HSD rather than a t test when comparing mean differences in ANOVA?
2. Samples were taken of individuals with each blood type to see if the average white blood cell count differed among types. Ten individuals in each group were sampled. The results are given in the table below:
Average White Blood Cell Count by Blood Type
|
A
|
B
|
AB
|
O
|
Grand Totals
|
|
5,000
|
7,000
|
7,200
|
5,550
|
|
|
5,550
|
7,500
|
7,770
|
6,570
|
|
|
6,000
|
8,500
|
8,600
|
7,620
|
|
|
6,500
|
5,000
|
6,000
|
5,900
|
|
|
8,000
|
6,100
|
5,950
|
7,100
|
|
|
7,700
|
7,200
|
7,540
|
6,980
|
|
|
10,000
|
9,900
|
11,000
|
8,750
|
|
|
6,100
|
6,400
|
6,200
|
7,700
|
|
|
7,200
|
7,300
|
7,000
|
8,100
|
|
|
5,500
|
5,800
|
6,100
|
4,900
|
|
|
9,000
|
8,950
|
7,800
|
5,800
|
|
|
2,x
|
76,550
|
79,650
|
81,160
|
74,970
|
312,330 (grand total)
|
|
x
|
7655.0
|
7965.0
|
8116.0
|
7497.0
|
7808.25 (grand mean)
|
Source: Modification to Exercise 10.9, page 171, Kuzma and Bohnenblust (2001).
a. State the null hypothesis.
b. Construct an ANOVA table.