Pearson’s Correlation Coefficient IB MATH SL CH 21B Pearson’s Correlation Coefficient

Pearson’s product-moment correlation coefficient Just observing points on a scatter plot to determine a linear relationship is inaccurate. Pearson r is a more precise measure of strength of linear correlation between two variables.

Pearson R The values of r range from -1 to +1. The sign of r indicates direction. Positive Correlation - an increase in one of the variables will result in an increase in the other. Negative Correlation – an increase in one of the variables will result in a decrease in the other. The size of r indicates the strength of the correlation. A value of r close to +1 or -1 indicates a strong correlation. A value or r close to zero indicates a weak correlation.

Positive p.551 NEGATIVE Positive Negative

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IB MATH SL CH 21C Line of Best Fit

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