Product moment correlation coefficient Quiz

1. $S_{xx}=25$, $S_{yy}=16$ and $S_{xy}=-15$. Find $r$.

• A. $-0.6$
• B. $-0.75$
• C. $-0.9375$
• D. $0.6$

2. Which of these cannot be a value of the product moment correlation coefficient?

• A. $-0.95$
• B. $0$
• C. $0.3$
• D. $1.4$

3. $r=-0.92$ for the number of hours of TV watched per week and test score. Which is the best description?

• A. Strong positive linear correlation
• B. Weak negative linear correlation
• C. Strong negative linear correlation
• D. 92% of students watch less TV

4. Heights are converted from centimetres to metres. What happens to $r$ between height and weight?

• A. It is divided by 100
• B. It is unchanged
• C. It is multiplied by 100
• D. It changes sign

5. A scatter of data follows a clear U-shape and $r$ is close to 0. What is the best conclusion?

• A. There is no relationship between the variables
• B. The calculation must be wrong
• C. The variables are independent
• D. There is no linear correlation, but there may be a non-linear relationship