Chapter 1. The Chi-Square Test Statistic

Correct. This is a correct statement.

Incorrect. This is a correct statement.

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Correct. Since the numerator is squared and the denominator is always positive, the chi-square test statistic value is always positive.

Incorrect. Since the numerator is squared and the denominator is always positive, the chi-square test statistic value is always positive.

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Correct. When the observed count equals its respective expected count, the chi-square test statistic is zero and the closer they are, the smaller the test statistic is.

Incorrect. When the observed count equals its respective expected count, the chi-square test statistic is zero and the closer they are, the smaller the test statistic is.

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Correct. The farther the observed count is from the expected count, the larger the chi-square test statistic. Thus, the larger the test statistic, the more evidence against the null hypothesis of “no relationship.”

Incorrect. The farther the observed count is from the expected count, the larger the chi-square test statistic. Thus, the larger the test statistic, the more evidence against the null hypothesis of “no relationship.”

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Correct. We use a chi-square distribution to find a P-value for a chi-square test statistic.

Incorrect. We use a chi-square distribution to find a P-value for a chi-square test statistic.

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Correct. The degrees of freedom for the chi-square test statistic are (r – 1)(c – 1).

Incorrect. The degrees of freedom for the chi-square test statistic are (r – 1)(c – 1).

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Correct. The appropriate null hypothesis says: There is NO association between student smoking and parent’s smoking.

Incorrect. The appropriate null hypothesis says: There is NO association between student smoking and parent’s smoking.

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Correct. The values given in the table are the counts observed in the data.

Incorrect. The values given in the table are the counts observed in the data.

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Correct. We assume the null hypothesis of no relationship to be true and use the marginals to find the expected counts.

Incorrect. We assume the null hypothesis of no relationship to be true and use the marginals to find the expected counts.

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Correct. All expected counts are bigger than 5 so the chi-square test statistic will have an approximate chi-square distribution.

Incorrect. All expected counts are bigger than 5 so the chi-square test statistic will have an approximate chi-square distribution.

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Correct. We have a term in the chi-square test statistic for every cell in the table.

Incorrect. We have a term in the chi-square test statistic for every cell in the table.

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Correct. “r” is the letter “r” for a reason; it represents the number of rows in the table.

Incorrect. “r” is the letter “r” for a reason; it represents the number of rows in the table.

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Correct. Since P-value = 0.000 is less than α = 0.02, we reject H₀.

Incorrect. Since P-value = 0.000 is less than α = 0.02, we reject H₀.

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Correct. When we reject H₀, we conclude that H_a is correct. In this situation, we conclude that there is a relationship.

Incorrect. When we reject H₀, we conclude that H_a is correct. In this situation, we conclude that there is a relationship.

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Correct. The value of 16.83 is in the same position in the computation as the cell “neither parent smokes/student smokes” lies in the two-way table.

Incorrect. The value of 16.83 is in the same position in the computation as the cell “neither parent smokes/student smokes” lies in the two-way table.

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Correct. Yes, we can conclude that the smoking rate of students is higher when both parents smoke than when neither parent smokes.

Incorrect. Yes, we can conclude that the smoking rate of students is higher when both parents smoke than when neither parent smokes.

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