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Statistics vocabulary · Descriptive Statistics

Standard deviation

Meaning in statistics, with examples

/ˈstændərd ˌdiːviˈeɪʃən/nounCore term

In statistics, standard deviation means: A measure of how spread out values are around the mean; a small value means the data sit close to the mean, a large one means they are widely scattered.

In Turkish: standart sapma

How it is used

Reported almost every time a mean is reported, often abbreviated SD (σ for a population, s for a sample). It is the square root of the variance and is expressed in the same units as the data, which makes it easier to interpret.

Example sentences

  1. Scores had a mean of 72 and a standard deviation of 9.

  2. In a normal distribution, about 95% of values lie within two standard deviations of the mean.

Common collocations

  • calculate the standard deviation
  • one standard deviation above the mean
  • sample standard deviation
  • large standard deviation
  • varianceThe average of the squared distances between each value and the mean; it measures spread, and its square root is the standard deviation.
  • meanThe sum of all the values divided by the number of values; the usual 'average' that describes the centre of a set of numbers.
  • standard errorThe standard deviation of an estimate, such as a sample mean, across repeated samples; it shows how precise the estimate is likely to be.
  • 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.
  • rangeThe difference between the largest and the smallest value in a data set; the simplest measure of spread.

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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