Result
Enter values and select Calculate.
Formula and method
Pearson r divides the sum of paired deviations from the two means by the square root of the two sums of squared deviations. The engine updates means, variation, and covariance together to reduce large-offset rounding error. It requires variation in both variables.
Worked example
For X = 1, 2, 3 and Y = 2, 4, 6, Pearson r is 1. Reversing Y to 6, 4, 2 gives r = −1.
Assumptions and boundaries
- Pearson r measures linear association; it does not establish causation.
- At least two paired observations are required, and both variables must vary.
- Pearson only is supported in Cohort 40; Spearman ranks are not silently substituted.
- No significance conclusion is generated. Use the P Value Calculator only when a suitable test statistic and study design are already established.
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