Analysis of whether two categorical variables, X = course subject and Y = grade earned by a student was conducted. Researchers selected n 800 students for their study using m = 4 distinct courses and k = 6 grades, from A to F and W. They evaluated a x? test statistic for testing independence between X and Y equal to TS = 29.64 At the significance level a = 0.01, do researchers have sufficient evidence that X and Y are dependent? 1. Show critical value (or values) needed for this procedure 2. Formulate the rejection rule

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**Chi-Square Test for Independence: Analysis of Categorical Variables**

In a study analyzing the relationship between two categorical variables, $X =$ course subject and $Y =$ grade earned by a student, researchers selected $n = 800$ students. The study examined $m = 4$ distinct courses and $k = 6$ grades, from $A$ to $F$ and $W$. To test the independence between $X$ and $Y$, they calculated a chi-square ($\chi^2$) test statistic of:

\[ \text{TS} = 29.64 \]

The primary question is whether, at the significance level $\alpha = 0.01$, there is sufficient evidence to conclude that $X$ and $Y$ are dependent.

**Steps to Analyze the Test:**

1. **Critical Value:**
   - Determine the critical value (or values) necessary for this procedure, based on degrees of freedom and the significance level.

2. **Rejection Rule:**
   - Formulate the rejection rule for the test, using the critical value to decide if the null hypothesis should be rejected.

3. **Decision Making:**
   - State your decision regarding the null hypothesis of independence, considering the calculated test statistic and the significance level $\alpha = 0.01$.

**Solution:**

To solve this problem, calculate the degrees of freedom for the chi-square test using the formula:

\[ \text{df} = (m - 1)(k - 1) \]

Next, find the critical value from the chi-square distribution table corresponding to $\alpha = 0.01$ and the calculated degrees of freedom. Compare the test statistic to this critical value to determine whether to reject the null hypothesis of independence.

This approach provides a step-by-step method to assess the dependency between course subjects and grades earned by students.
Transcribed Image Text:**Chi-Square Test for Independence: Analysis of Categorical Variables** In a study analyzing the relationship between two categorical variables, $X =$ course subject and $Y =$ grade earned by a student, researchers selected $n = 800$ students. The study examined $m = 4$ distinct courses and $k = 6$ grades, from $A$ to $F$ and $W$. To test the independence between $X$ and $Y$, they calculated a chi-square ($\chi^2$) test statistic of: \[ \text{TS} = 29.64 \] The primary question is whether, at the significance level $\alpha = 0.01$, there is sufficient evidence to conclude that $X$ and $Y$ are dependent. **Steps to Analyze the Test:** 1. **Critical Value:** - Determine the critical value (or values) necessary for this procedure, based on degrees of freedom and the significance level. 2. **Rejection Rule:** - Formulate the rejection rule for the test, using the critical value to decide if the null hypothesis should be rejected. 3. **Decision Making:** - State your decision regarding the null hypothesis of independence, considering the calculated test statistic and the significance level $\alpha = 0.01$. **Solution:** To solve this problem, calculate the degrees of freedom for the chi-square test using the formula: \[ \text{df} = (m - 1)(k - 1) \] Next, find the critical value from the chi-square distribution table corresponding to $\alpha = 0.01$ and the calculated degrees of freedom. Compare the test statistic to this critical value to determine whether to reject the null hypothesis of independence. This approach provides a step-by-step method to assess the dependency between course subjects and grades earned by students.
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