The Pearson product-moment correlation coefficient is a statistic that is used to estimate the degree of linear relationship between two variables. It is a numerical estimate of both the strength of the linear relationship and the direction of the relationship. The Pearson product-moment correlation coefficient is calculated when the scale of measurement is interval or ratio; it is also used on approximately interval data. This statistic is typically referred to as the "correlation" or "correlation coefficient".

The correlation coefficient ranges in value between -1.0 and +1.0. To interpret the correlation coefficient, we must consider both its sign (positive or negative) and its absolute value. A perfect positive correlation has a coefficient of 1.0; a perfect negative correlation has a coefficient of -1.0. When there is no association between two variables, the correlation coefficient has a value of 0.

Review each correlation coefficient presented below and determine its direction and strength. Click on the correlation coefficients to check your interpretation.

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