Median absolute deviation: what it means and how to read it
In the report: mad — The median of the absolute deviations from the median, without the 1.4826 factor.
How to read it
A spread that ignores extreme values. Multiplied by 1.4826 it estimates std for normal data; some programs show it that way, this one does not.
In plain words
A shop wrote down seven bills: 20, 22, 25, 25, 28, 30 and 400 dollars. The middle bill is 25. With the odd 400 dollar bill in, the standard deviation jumps to about 140, which says little about the usual customer. The owner wanted a number for the usual gap that one odd bill cannot spoil. She asked for mad: it looks at how far each bill is from 25 and takes the middle of those gaps. It came out 3. Now she can say that a usual bill is within about 3 dollars of 25. Some programs show a bigger, stretched version of mad; this add-on shows it plain.
How it is computed
median(|x − median|)Where you see it
STATS_DESCRIPTIVE— Column-wise descriptive statistics with flexible metric selection and optional column filtering.
Related values
- Geometric mean — The n-th root of the product of the values; zero and tiny values are raised to epsilon (Settings), a negative value gives an empty cell.
- Harmonic mean — n divided by the sum of 1/x; zero and tiny values are raised to epsilon (Settings), a negative value gives an empty cell.
- Flatness — The geometric mean of the values as they are divided by their arithmetic mean, without epsilon: a zero among the values gives exactly 0; empty when the mean is 0 or a value is negative.
- Spectral flatness — The geometric mean divided by the arithmetic mean of the shares x² / Σ x².
- Slope from the first to the last value — (last value − first value) / (n − 1), in row order; empty for fewer than 2 values, 0 for a constant.
Get it in your sheet
One formula in a cell gives the whole report, Median absolute deviation included. ALS Stats is a free add-on for Google Sheets™.
Install ALS Stats from Google Workspace Marketplace (opens in a new tab)