What are Pearson's r and scatterplots?

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Pearsonís r

 

Sometimes we want to know whether two variables are related to one another. If they are related, we want to know how much. Is there a strong relationship between two variables or is it a weak relationship? What is the direction of the relationship?

 

When one variable goes up, does the other go down? Pearsonís r can help us with that. Pearsonís r is a statistic that helps you understand the strength of the linear relationship between two variables.

When r isÖ

 

  • Close to 1, there is a strong relationship between your two variables.

  • Close to 0, there is a weak relationship between your two variables.

  • Positive (+), as one variable increases in value, the second variable also increases in value. This is called a positive correlation.

  •  Negative (-), as one variable increases in value, the second variable decreases in value. This is called a negative correlation.

Scatterplots

 

These are graphs that often accompany the Pearsonís r statistic. These graphs help us understand the relationship between the two variables. They have lots of dots. Each dot signifies a data point that represents values of both variables.



 

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