H-Spread

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The H-spread range is a measure of variability, spread or dispersion. It is the difference between the 75th percentile (often called Q3) and the 25th percentile (Q1). The formula for the H-spread is therefore: Q3-Q1. It is sometimes called the interquartile range. although not used extensively, the H-spread is a stable measure of spread and perhaps should be in more common usage.