Statistics

Understanding Z-Scores in Statistics

By SC Editorial 2026-06-03 7 min read

A z-score tells you how many standard deviations a value is from the mean. It standardizes data for comparison across different scales.

Formula

z = (x - mean) / std_dev. Calculate instantly with our Z-Score Calculator.

Interpretation

|z| < 1 is common. |z| > 2 is unusual. |z| > 3 is rare. Positive z means above mean; negative means below.

Applications

Z-scores compare test results across exams, identify outliers in quality control, and feed into normal distribution probability tables.

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