400 CHAPTER 6 Inferential Statistics
(Remember, the smaller this error becomes, the larger the probability
βbecomes of making a Type II error.) The most typical rejection level
isα= 5%. As mentioned above, the test statistic becomes
X−μ
σ/√
n.
This is normally distributed with mean 0 and variance 1. The 5%
rejection region is dependent upon the alternative hypothesis. It’s
easiest just to draw these:
H 0 : μ=μ 0 , Ha: μ 6 =μ 0.
H 0 : μ=μ 0 , Ha: μ < μ 0.
H 0 : μ=μ 0 , Ha: μ > μ 0.