Correlation Coefficient Calculator
Paste two data sets as x,y pairs to find the Pearson correlation coefficient r and r squared. r ranges from -1 (perfect inverse) to +1 (perfect direct), with 0 meaning no linear relationship.
How to find the correlation coefficient
- Enter your paired data, one x,y pair per line.
- Read off r, the strength and direction of the linear relationship.
- Use r squared to see the share of variance the relationship explains.
Examples
A moderately positive relationship
1,2 2,4 3,5 4,4 5,5
r = 0.774597, r squared = 0.6, n = 5
Frequently asked questions
What does the correlation coefficient mean?
Pearson r measures the strength and direction of a straight-line relationship between two variables. Values near +1 or -1 are strong; values near 0 are weak.
What is the difference between r and r squared?
r squared is simply r multiplied by itself. It is the proportion of variance in one variable explained by a linear fit to the other, always between 0 and 1.
Does correlation prove causation?
No. A high correlation shows two variables move together, but it does not prove one causes the other. A hidden third factor can drive both.
Do the two data sets need the same number of values?
Yes. Each x value must pair with exactly one y value, so the two lists must be the same length, with at least two pairs.
Is the result a sample or population correlation?
They are identical. The sample (n-1) and population (n) divisors cancel in the formula, so Pearson r is the same either way.
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