For the sample x1, x2,…, xn, with mean , the mean absolute deviation is equal to
It is a measure of dispersion but is not often used as variance has preferable algebraic properties.
A measure of spread. For observations x1, x2,…, xn, with sample mean x̄ and median m, the mean absolute deviation about the mean is
and the mean absolute deviation about the median is 
- Haldane, Richard Burdon, Viscount Haldane of Cloan (1856–1928)
- Halder, Franz (1884–1972)
- Haleakala Observatory
- Hale, Alan
- Hale cycle
- Hale, George Ellery
- Hale, George Ellery (1868–1938)
- Hale Observatories
- Hales, Stephen
- Hale Telescope
- Halevi, Judah (c.1075–1141)
- Hale–Bopp
- Hale–Bopp, Comet
- Hale’s law
- half-adder
- half cell
- half-cell
- half chair
- half duplex
- half-duplex
- half duplex communication
- half-duplex operation
- half-field prism
- half-graben
- half-height factor