Correlation and regression Quiz

1. A scatter graph has $r=-0.15$. How would you describe the correlation?

• A. Strong negative
• B. Weak negative
• C. Weak positive
• D. Strong positive

2. The line of best fit for revision hours $x$ and marks $y$ is $y=4x+12$. What does the gradient mean?

• A. Each extra mark needs 4 more hours of revision
• B. A student with no revision scores 4
• C. The correlation is 4
• D. Each extra hour of revision adds about 4 marks

3. Data are collected for $x$ between 10 and 50. Which prediction is an interpolation?

• A. $x=35$
• B. $x=60$
• C. $x=5$
• D. $x=100$

4. For two variables, $r=0.05$. What is the best conclusion?

• A. Strong positive correlation
• B. Strong negative correlation
• C. Almost no linear correlation
• D. Perfect correlation

5. Why is extrapolation less reliable than interpolation?

• A. It uses a different equation
• B. The pattern may not continue outside the range of the data
• C. The correlation becomes negative
• D. The value of $r$ changes sign