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Statistics vocabulary · Descriptive Statistics

Outlier

Meaning in statistics, with examples

/ˈaʊtlaɪər/nounCore term

In statistics, outlier means: An observation that lies unusually far from most of the other values in a data set; it may come from an error or from a genuinely unusual case.

In Turkish: aykırı değer, uç değer

How it is used

Analysts detect, check, remove or keep outliers, and should always say how they handled them. A common rule flags values more than 1.5 × IQR beyond the quartiles, which is also how box plots mark them.

Example sentences

  1. One participant reported working 160 hours a week, which is clearly an outlier.

  2. The results were similar with and without the three outliers.

Common collocations

  • detect outliers
  • remove outliers
  • extreme outlier
  • sensitive to outliers
  • box plotA chart that shows the median, the quartiles and the spread of the data as a box with lines (whiskers) extending from it, with outliers marked as separate points.
  • interquartile rangeThe distance between the first and third quartiles (Q3 − Q1), showing how spread out the middle 50% of the data is.
  • meanThe sum of all the values divided by the number of values; the usual 'average' that describes the centre of a set of numbers.
  • medianThe middle value when the data are put in order from smallest to largest; with an even number of values, it is the mean of the two middle ones.
  • z-scoreA value showing how many standard deviations an observation lies above or below the mean, found by subtracting the mean and dividing by the standard deviation.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Descriptive Statistics

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