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IEVref: | 103-08-12 | ID: | |

Language: | en | Status: Standard | |

Term: | variance, <in statistics> | ||

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Definition: | measure of dispersion equal to the sum of the squared deviations from the mean value divided by the number of deviations or by that number minus 1, depending upon the cases considered: (1) variance of the whole population of (2) variance of the sample of (3) estimate of the variance of the population from a sample: $\frac{1}{n-1}{\displaystyle \sum _{j=1}^{n}({x}_{j}}-\overline{X}{)}^{2}$ where $\overline{X}$ is the mean value of the items of observation $x}_{j$ considered | ||

Publication date: | 2009-12 | ||

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Internal notes: | 2017-02-20: Editorial revisions in accordance with the information provided in C00020 (IEV 103) - evaluation. JGO | ||

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(1) variance of the whole population of *N* items: $\frac{1}{N}{\displaystyle \sum _{j=1}^{N}({x}_{j}}-\overline{X}{)}^{2}$

(2) variance of the sample of *n* observations: $\frac{1}{n}{\displaystyle \sum _{j=1}^{n}({x}_{j}}-\overline{X}{)}^{2}$

(3) estimate of the variance of the population from a sample: $\frac{1}{n-1}{\displaystyle \sum _{j=1}^{n}({x}_{j}}-\overline{X}{)}^{2}$

where $\overline{X}$ is the mean value of the items of observation $x}_{j$ considered