If the assumptions for a nonpooled \(t-\)interval are satisfied, the formula for a \((1-\alpha)\) level lower confidence bound for the difference, \(\mu_{1}-\mu{2}\), between two population means is

\((\bar{x_{1}}-\bar{x_{2}})-t_{\alpha}\cdot \sqrt{(s_{1}^{2}/n_{1})+(s_{2}^{2}/n_{2})}\)

For a right tailed hypothesis test at the significance level \(\alpha\), the null hypothesis \(H_{0}:\mu_{1}=\mu_{2}\) will be rejected in favor of the alternative hypothesis \(H_{a}:\mu_{1}>\mu_{2}\) if and only if the \((1-\alpha)\) level lower confidence bound for \(\mu_{1}-\mu_{2}\) is greater than or equal to \(0\). In each case, illustrate the preceding relationship by obtaining the appropriate lower confidence bound and comparing the result to the conclusion of the hypothesis test in the specified exercise.

a. Exercise \(10.82\)

b. Exercise \(10.85\)

Short Answer

Expert verified

Part a. It can be concluded that test results are statistically significant at \(1%\) level of significant.

Part b. It can be concluded that test results are statistically significant at \(1%\) level of significant.

Step by step solution

01

Part a. Step 1. Explanation

Consider the data,

It can be concluded that test results are statistically significant at \(1%\) level of significant.

02

Part b. Step 1. Explanation

Consider the data,

It can be concluded that test results are statistically significant at \(1%\) level of significant.

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Most popular questions from this chapter

A hypothesis test is to be performed to compare the means of two populations, using a paired sample. The sample of 15 paired differences contains an outlier but otherwise is roughly bell-shaped. Assuming that it is not legitimate to remove the outlier, which test is better to use-the paired t-test or the paired Wilcoxon signed-rank test? Explain your answer,

The intent is to employ the sample data to perform a hypothesis test to compare the means of the two populations from which the data were obtained. In each case, decide which of the procedures should be applied.

Independent: n1=25

n2=20

Two-Tailed Hypothesis Tests and CIs. As we mentioned on page 413, the following relationship holds between hypothesis tests and confidence intervals: For a two-tailed hypothesis test at the significance level α, the null hypothesis H0:μ1=μ2 will be rejected in favor of the alternative hypothesis H2:μ1μ2 if and only if the (1-α)-level confidence interval for μ1-μ2 does not contain 0. In each case, illustrate the preceding relationship by comparing the results of the hypothesis test and confidence interval in the specified exercises.

a. Exercises 10.81 and 10.87

b. Excrcises 10.86 and 10.92

Suppose that you want to perform a hypothesis test to compare the means of two populations, using a paired sample. For each part, decide whether you would use the paired t-test, the paired Wilcoxon signed-rank test, or neither of these tests if preliminary data analyses of the sample of paired differences suggest that the distribution of the paired-difference variable is

a. uniform.

b. neither symmetric nor normal; the sample size is 132.

c. moderately skewed but otherwise roughly bell-shaped.

Suppose that you want to perform a hypothesis test to compare the means of two populations, using a paired sample. For each part, decide whether you would use the pairedt -test, the paired Wilcoxon signed-rank test, or neither of these tests if preliminary data analyses of the sample of paired differences suggest that the distribution of the paired-difference variable is

a. approximately normal.

b. highly skewed; the sample size is 20.

c. symmetric bimodal.

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