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Chapter 12

4.3 The coefficient of determination

This squares the correlation in order to express the strength of the relationship
between the variables as a percentage.

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The coefficient of determination, r , gives the proportion of changes in y that can be
explained by changes in x, assuming a linear relationship between x and y.

For example:

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If a correlation coefficient r = +0.9, then r = 0.81 and we could state that 81% of the
observed changes in y can be explained by the changes in x and that 19% of the
changes must be due to other factors.

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