Correlation measures the strength and direction of a linear relationship between two variables.
r = 1: Perfect positive correlation. r = −1: Perfect negative. r = 0: No correlation.
R² tells you the proportion of variance in Y explained by X.
Use this statistical calculator when you need a rigorous, reportable result — not a rough estimate. The formula is standard, but manual computation on large datasets introduces errors that undermine any subsequent analysis.
A frequent mistake is computing statistics on a dataset without checking for data entry errors, outliers, or missing values. A single transcription error in a small dataset can shift the mean and standard deviation substantially. Always verify the input data before interpreting results.
A quality engineer analyses the diameter measurements of 25 machined parts: mean 50.02 mm, standard deviation 0.08 mm. With a tolerance of ±0.25 mm, the process is well within specification — and the SD confirms the manufacturing variation is low enough that virtually no parts will fall outside tolerance.
r = 0.8 indicates a strong positive correlation between the two variables.
CalcPlanet – Free Online Calculators
725+ free calculators and 108 tools for math, money, health, and everyday life. Instant results, verified formulas, no sign-up.
By CalcPlanet Editorial · Reviewed against our Editorial Standards and Formula Sources.
CalcPlanet calculators are free, privacy-first, and formula-reviewed.
Editorial Standards · Formula Sources · Privacy · Terms · Contact
