文档介绍：Two-sample Tests of Hypothesis
Chapter 11
GOALS
Conduct a test of a hypothesis about the difference between two i Find the appropriate test statistic.
Because both samples are more than 30, we can use z-distribution as the test statistic.
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Example 1 continued
Step 4: State the decision rule.
Reject H0 if Z > Z
Z >
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Example 1 continued
Step 5: Compute the value of z and make a decision
The computed value of is larger than the critical value of . Our decision is to reject the null hypothesis. The difference of .20 minutes between the mean checkout time using the standard method is too large to have occurred by chance. We conclude the U-Scan method is faster.
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Two-Sample Tests about Proportions
Here are several examples.
The vice president of human resources wishes to know whether there is a difference in the proportion of hourly employees who miss more than 5 days of work per year at the Atlanta and the Houston plants.
General Motors is considering a new design for the Pontiac Grand Am. The design is shown to a group of potential buyers under 30 years of age and another group over 60 years of age. Pontiac wishes to know whether there is a difference in the proportion of the two groups who like the new design.
A consultant to the airline industry is investigating the fear of flying among adults. Specifically, the company wishes to know whether there is a difference in the proportion of men versus women who are fearful of flying.
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Two Sample Tests of Proportions
We investigate whether two samples came from populations with an equal proportion of successes.
The two samples are pooled using the following formula.
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Two Sample Tests of Proportions continued
The value of the test statistic is computed from the following formula.
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Manelli Perfume Company recently developed a new fragrance that it plans to market under the name Heavenly. A number of market studies indicate that Heavenly has very good market pot