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## Statistics and probability

### Course: Statistics and probability>Unit 5

Lesson 2: Correlation coefficients

# Correlation coefficient review

The correlation coefficient r measures the direction and strength of a linear relationship. Calculating r is pretty complex, so we usually rely on technology for the computations. We focus on understanding what r says about a scatterplot.

### What is a correlation coefficient?

The correlation coefficient r measures the direction and strength of a linear relationship. Calculating r is pretty complex, so we usually rely on technology for the computations. We focus on understanding what r says about a scatterplot.
Here are some facts about r:
• It always has a value between minus, 1 and 1.
• Strong positive linear relationships have values of r closer to 1.
• Strong negative linear relationships have values of r closer to minus, 1.
• Weaker relationships have values of r closer to 0.
Let's look at a few examples: