Question

What is the r-value of the following data to three decimal places?

Answer 1

The correlation coefficient is A. -0.985.

Explanation:

The correlation coefficient r measures the direction and strength of a linear relationship.

• It always has a value between -1, and 1.
• Strong positive linear relationships have values of r closer to 1.
• Strong negative linear relationships have values of r closer to -1.
• Weaker relationships have values of r closer to 0.

To find the r-value of the following data:

`\left\begin{array}cX&5&7&10&15&19\\Y&19&17&16&12&7\end{array}\right`

Step 1: Find
`X\cdot Y`,
`X\cdot X` and
`Y\cdot Y` as it was done in the table below.

Step 2: Find the sum of every column as it was done in the first image below.

Step 3: Use the following formula to work out the correlation coefficient as it was done in the second image below.