Calculate correlation

Calculate Pearson correlation and the coefficient of determination for paired numeric observations.

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ToolCorrelation Calculator
Input
Output
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How it works

Pearson r divides the centered cross-product of two lists by the product of their centered sums of squares; r² is its squared value. The calculation reports association for the supplied sample and avoids universal strength labels because practical meaning depends on the field and study design.

  • Both lists must contain paired observations and each must vary.

Worked example

Two lists of five points
Paired x and y readings
Input
											X values: [1,2,3,4,5]
Y values: [2,4,5,4,5]
Output
												N: 5
R: 0.7746
R squared: 0.6
Strength: Strong positive

When to use this

Quality-control measurements, experiment summaries, and exploratory data analysis calculate paired association.

Edge cases

  • A constant list has zero standard deviation, so r is undefined.
  • A single outlier can move r substantially.
  • Correlation does not establish that one variable causes the other.

References