Contingency tables and the chi-squared test Quiz

1. What are the degrees of freedom for a contingency table with 4 rows and 3 columns?

• A. $6$
• B. $12$
• C. $11$
• D. $7$

2. A cell has row total 40, column total 30 and grand total 120. Find its expected frequency.

• A. $70$
• B. $15$
• C. $10$
• D. $40$

3. A cell has $O=30$ and $E=24$. Find its contribution to the test statistic.

• A. $0.25$
• B. $1.5$
• C. $6$
• D. $1.2$

4. Which statement is the convention for the chi-squared test?

• A. All observed frequencies must be equal
• B. The grand total must exceed 100
• C. The table must be square
• D. All expected frequencies should be greater than 5

5. A test with $\nu=3$ gives $X^2=9.1$. At the $5\%$ level (critical value $7.815$), what is the conclusion?

• A. Do not reject $H_0$ because $9.1>7.815$
• B. Reject $H_0$ because $9.1<7.815$
• C. Reject $H_0$ because $9.1>7.815$
• D. Do not reject $H_0$ because $9.1<7.815$