# Outlier

*Math & Statistics — Finicade finance glossary*

An outlier is an observation far from the rest of the data. The decision that matters is whether it's an error or a signal: a fat-finger price is noise to be cleaned, while a crash day is the single most informative observation in a risk dataset. Deleting outliers because they inconvenience a model is the most common way to build something that works beautifully until the day it matters.

**Also known as:** outliers, extreme observation, anomaly

**Related terms:** [Mean, Median and Mode](https://finicade.com/glossary/mean-median-mode), [Interquartile Range](https://finicade.com/glossary/interquartile-range), [Fat Tails](https://finicade.com/glossary/fat-tails), [Ordinary Least Squares](https://finicade.com/glossary/ordinary-least-squares), [Kurtosis](https://finicade.com/glossary/kurtosis)

**Taught in:** Stat Dojo — The Average & the Median

Source: https://finicade.com/glossary/outlier