The contingency table shows the results of a random sample of high school students with respect to year and grade point average. At the significance level, a=0.05, test the claim that at least two of the variables are dependent. Use the Independence #2 calculator to test the hypothesis. Fill in the contingency table for row and columns based on the results. Also fill in the space for the level of significance a H_O: The variables are independent H_a: At least two of the variables are dependent (claim) a.) Find the degrees of freedom, the critical value and identify the rejection region. b.) Find the chi-square test statistic c.) Is the test statistic in the rejection region? How do you know? d.) Do we reject or fail to reject the null hypothesis? e.) Is there enough evidence to support the claim that at least two of the variables are dependent? Give a full conclusion statement including the level of significance.

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**Title: Chi-Square Test for Independence: Educational Exercise on Contingency Tables**

The following exercise provides a practical approach to understanding the chi-square test for independence. We use a contingency table displaying the results of a random sample of high school students categorized by year and grade point average. The task is to test, at a significance level of \( \alpha = 0.05 \), the claim that there is a dependency between at least two of the variables.

**Hypothesis Testing:**

- **Null Hypothesis (\( H_0 \)):** The variables are independent.
- **Alternative Hypothesis (\( H_a \)):** At least two of the variables are dependent (claim).

**Instructions:**

1. **Use the Independence \#2 Calculator:**
   - Fill in the contingency table for the rows and columns based on the results.
   - Input the level of significance \( \alpha = 0.05 \).

2. **Tasks:**

   a.) **Find the Degrees of Freedom, Critical Value, and Rejection Region:**
   - Determine the degrees of freedom for the contingency table.
   - Find the corresponding critical value using the chi-square distribution table.
   - Identify the rejection region based on the critical value and \( \alpha \).

   b.) **Find the Chi-Square Test Statistic:**
   - Calculate the test statistic using the formula for chi-square tests.

   c.) **Assess the Test Statistic:**
   - Check if the test statistic falls within the rejection region.
   - Provide reasoning for your conclusion.

   d.) **Decision on the Null Hypothesis:**
   - Based on the test statistic, choose to reject or fail to reject the null hypothesis.

   e.) **Conclusion Statement:**
   - Discuss if there is sufficient evidence to support the claim of dependency between the variables.
   - Provide a comprehensive conclusion including the level of significance \( \alpha = 0.05 \).

This exercise is designed to enhance understanding of hypothesis testing and contingency tables, guiding learners through practical statistical analysis.
Transcribed Image Text:**Title: Chi-Square Test for Independence: Educational Exercise on Contingency Tables** The following exercise provides a practical approach to understanding the chi-square test for independence. We use a contingency table displaying the results of a random sample of high school students categorized by year and grade point average. The task is to test, at a significance level of \( \alpha = 0.05 \), the claim that there is a dependency between at least two of the variables. **Hypothesis Testing:** - **Null Hypothesis (\( H_0 \)):** The variables are independent. - **Alternative Hypothesis (\( H_a \)):** At least two of the variables are dependent (claim). **Instructions:** 1. **Use the Independence \#2 Calculator:** - Fill in the contingency table for the rows and columns based on the results. - Input the level of significance \( \alpha = 0.05 \). 2. **Tasks:** a.) **Find the Degrees of Freedom, Critical Value, and Rejection Region:** - Determine the degrees of freedom for the contingency table. - Find the corresponding critical value using the chi-square distribution table. - Identify the rejection region based on the critical value and \( \alpha \). b.) **Find the Chi-Square Test Statistic:** - Calculate the test statistic using the formula for chi-square tests. c.) **Assess the Test Statistic:** - Check if the test statistic falls within the rejection region. - Provide reasoning for your conclusion. d.) **Decision on the Null Hypothesis:** - Based on the test statistic, choose to reject or fail to reject the null hypothesis. e.) **Conclusion Statement:** - Discuss if there is sufficient evidence to support the claim of dependency between the variables. - Provide a comprehensive conclusion including the level of significance \( \alpha = 0.05 \). This exercise is designed to enhance understanding of hypothesis testing and contingency tables, guiding learners through practical statistical analysis.
The table presents a distribution of students across different GPA ranges segmented by academic year level: Freshman, Sophomore, Junior, and Senior.

| GPA Range | Freshman | Sophomore | Junior | Senior |
|-----------|----------|-----------|--------|--------|
| Less than 1.00 | 20 | 24 | 20 | 18 |
| 1.00 - 1.99 | 40 | 40 | 44 | 58 |
| 2.00 - 2.99 | 93 | 90 | 87 | 83 |
| 3.00 - 3.99 | 125 | 105 | 116 | 117 |
| 4.00 +     | 38 | 23 | 24 | 33 |

- **Freshmen** have the highest count in the 3.00 - 3.99 GPA range (125 students) and the lowest in the Less than 1.00 range (20 students).
- **Sophomores** also peak in the 3.00 - 3.99 range (105 students), but their count in the 4.00+ range is the lowest (23 students).
- **Juniors** follow a similar pattern with the greatest number in the 3.00 - 3.99 range (116 students) and the least in the Less than 1.00 range (20 students).
- **Seniors** show a maximum in the 3.00 - 3.99 range (117 students) and a minimum in the Less than 1.00 range (18 students).

Overall, most students across all levels fall in the 3.00 - 3.99 GPA range, while the number decreases significantly in the Less than 1.00 range.
Transcribed Image Text:The table presents a distribution of students across different GPA ranges segmented by academic year level: Freshman, Sophomore, Junior, and Senior. | GPA Range | Freshman | Sophomore | Junior | Senior | |-----------|----------|-----------|--------|--------| | Less than 1.00 | 20 | 24 | 20 | 18 | | 1.00 - 1.99 | 40 | 40 | 44 | 58 | | 2.00 - 2.99 | 93 | 90 | 87 | 83 | | 3.00 - 3.99 | 125 | 105 | 116 | 117 | | 4.00 + | 38 | 23 | 24 | 33 | - **Freshmen** have the highest count in the 3.00 - 3.99 GPA range (125 students) and the lowest in the Less than 1.00 range (20 students). - **Sophomores** also peak in the 3.00 - 3.99 range (105 students), but their count in the 4.00+ range is the lowest (23 students). - **Juniors** follow a similar pattern with the greatest number in the 3.00 - 3.99 range (116 students) and the least in the Less than 1.00 range (20 students). - **Seniors** show a maximum in the 3.00 - 3.99 range (117 students) and a minimum in the Less than 1.00 range (18 students). Overall, most students across all levels fall in the 3.00 - 3.99 GPA range, while the number decreases significantly in the Less than 1.00 range.
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