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Ch. 7 - Hypothesis Testing with One Sample
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Not the one you use?Change textbook
Chapter 7, Problem 7.5.7

In Exercises 7–12, find the critical value(s) and rejection region(s) for the type of chi-square test with sample size n and level of significance α.


Right-tailed test, n=27,α=0.05

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Determine the degrees of freedom (df) for the chi-square test. The formula for degrees of freedom is df = n - 1, where n is the sample size. In this case, df = 27 - 1.
Identify the level of significance (α). For this problem, α = 0.05, which represents the probability of rejecting the null hypothesis when it is true.
Since this is a right-tailed test, locate the critical value of the chi-square distribution corresponding to df = 26 and α = 0.05. Use a chi-square distribution table or statistical software to find this value.
Define the rejection region. For a right-tailed test, the rejection region consists of all chi-square values greater than the critical value obtained in the previous step.
Summarize the results: The critical value and rejection region are now determined. The rejection region is where the test statistic exceeds the critical value, indicating evidence to reject the null hypothesis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Chi-Square Test

The chi-square test is a statistical method used to determine if there is a significant association between categorical variables. It compares the observed frequencies in each category to the frequencies expected under the null hypothesis. This test is commonly used in hypothesis testing to assess goodness-of-fit or independence.
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Critical Value

A critical value is a threshold that determines the boundary for rejecting the null hypothesis in hypothesis testing. It is derived from the chosen significance level (α) and the distribution of the test statistic. For a right-tailed chi-square test, the critical value indicates the point beyond which the test statistic is considered significant.
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Rejection Region

The rejection region is the range of values for the test statistic that leads to the rejection of the null hypothesis. In a right-tailed test, this region is located to the right of the critical value. If the calculated test statistic falls within this region, it suggests that the observed data is unlikely under the null hypothesis, prompting its rejection.
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Step 4: State Conclusion