Chapter 11: Problem 18
Describe in your own words a test of independence and a test of homogeneity. Give one example of each.
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Chapter 11: Problem 18
Describe in your own words a test of independence and a test of homogeneity. Give one example of each.
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A random sample of 1000 Americans was taken, and these adults were asked if experience in politics was necessary for a candidate to be president of America. The following table presents the results of the survey. $$ \begin{array}{lccc} \hline & \text { Necessary } & \text { Not Necessary } & \text { No Opinion } \\\ \hline \text { Men } & 260 & 220 & 70 \\ \text { Women } & 230 & 180 & 40 \\ \hline \end{array} $$ Test at a \(1 \%\) significance level whether gender and opinions are related.
Consider the following contingency table, which records the results obtained for four samples of fixed sizes selected from four populations. $$ \begin{array}{lcccc} \hline & \multicolumn{4}{c} {\text { Sample Selected From }} \\ \cline { 2 - 5 } & \text { Population 1 } & \text { Population 2 } & \text { Population 3 } & \text { Population 4 } \\ \hline \text { Row 1 } & 24 & 81 & 60 & 121 \\ \text { Row 2 } & 46 & 64 & 91 & 72 \\ \text { Row 3 } & 20 & 37 & 105 & 93 \\ \hline \end{array} $$ a. Write the null and alternative hypotheses for a test of homogeneity for this table. b. Calculate the expected frequencies for all cells assuming that the null hypothesis is true. c. For \(\alpha=.025\), find the critical value of \(\chi^{2}\). Show the rejection and nonrejection regions on the chi-square distribution curve. d. Find the value of the test statistic \(\chi^{2}\). e. Using \(\alpha=.025\), would you reject the null hypothesis?
Construct the \(95 \%\) confidence intervals for the population variance and standard deviation for the following data, assuming that the respective populations are (approximately) normally distributed. a. \(n=10, s^{2}=7.2\) b. \(n=18, s^{2}=14.8\)
Two random samples, one of 95 blue-collar workers and a second of 50 white- collar workers, were taken from a large company. These workers were asked about their views on a certain company issue. The following table gives the results of the survey. $$ \begin{array}{lccc} \hline & \multicolumn{3}{c} {\text { Opinion }} \\ \cline { 2 - 4 } & \text { Favor } & \text { Oppose } & \text { Uncertain } \\\ \hline \text { Blue-collar workers } & 44 & 39 & 12 \\ \text { White-collar workers } & 21 & 26 & 3 \\ \hline \end{array} $$ Using a \(2.5 \%\) significance level, test the null hypothesis that the distributions of opinions are homogeneous for the two groups of workers.
How is the expected frequency of a category calculated for a goodness-of-fit test? What are the degrees of freedom for such a test?
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