noun

outlier

OWT-lye-uh

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Outlier (noun) means a data point that sits far away from the rest of a set of results, and which may signal a real extreme case or a measurement error. Example: “One household reported an income of £4 million, an outlier that dragged the mean upwards.”

noun

A data point that sits far away from the rest of a set of results, and which may signal a real extreme case or a measurement error.

"One household reported an income of £4 million, an outlier that dragged the mean upwards."

"We removed two outliers before fitting the curve."

A person or thing that stands markedly apart from the others in a group.

"Among European capitals, its rents make it a real outlier."

"He was the outlier in a family of accountants."

In geology, an isolated area of younger rock surrounded by older rock, separated from the main body by erosion.

"The chalk outlier stands proud of the surrounding clay."

How to use outlier

Learner’s notes

In plain EnglishA result or person that sits well outside the normal range.

When to use it

Neutral; standard in statistics and increasingly common in general writing.

Memory tip

In everyday use calling someone an outlier is usually admiring or simply descriptive, not critical.

Trace the full origin ↓

Easily confused with

anomaly → exception → extreme value noise →

Common pairings

statistical outlier remove outliers a clear outlier outlier detection

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C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

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Fill the gap

Can you complete this real example?

One household reported an income of £4 million, an _____ that dragged the mean upwards.

Etymology

From out and the verb lie, meaning something lying outside the main body; the geological sense is recorded before the statistical one.

Origin: English

Synonyms

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anomaly aberration exception deviation one-off maverick odd one out

Antonyms

norm average

Related words

change common beautiful average normal except rule fair

Rhymes for outlier

bier tier pier crier skier trier Meier Grier Drier Xavier copier vizier

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Frequently asked questions

What is the difference between an outlier and an anomaly?

An outlier is defined statistically: it lies far from the rest of the distribution. An anomaly implies something is genuinely wrong or unexplained. Every anomaly may look like an outlier, but many outliers are legitimate extreme values rather than errors.

Should you remove outliers from your data?

Only if you can justify it. Remove a point when you have evidence it is a recording or measurement error. Removing points simply because they are inconvenient biases the result, and in skewed data a median or a robust method is a better answer than deletion.

How are outliers identified?

Common rules are values more than 1.5 times the interquartile range beyond the first or third quartile, or more than about three standard deviations from the mean. Both are conventions, not laws, and the right threshold depends on the data.

What is the meaning of outlier?

"outlier" (noun) means a data point that sits far away from the rest of a set of results, and which may signal a real extreme case or a measurement error.

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change common beautiful average normal except rule fair