Z-score

Z-score or standard score is a statistical measurement that describes a value's relationship to the mean of a group of values. Z-score is measured in terms of standard deviations from the mean. If a Z-score is 0, it indicates that the data point's score is identical to the mean score. A Z-score of 1.0 would indicate a value that is one standard deviation from the mean. Z-scores may be positive or negative, with a positive value indicating the score is above the mean and a negative score indicating it is below the mean.

Calculation

The Z-score is calculated using the following formula:

Z = (X - μ) / σ

Where:

• Z is the Z-score,
• X is the value of the element,
• μ is the population mean,
• σ is the standard deviation.

Uses

Z-scores are used by researchers in a variety of fields. They are commonly used in the fields of healthcare, finance, weather forecasting, and more. They are used to compare the results of different surveys or experiments, to find out if a data point is typical for a given data set or if it is atypical.

See also

• Standard deviation
• Mean
• Statistical significance

References

Z-score Resources
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