Bessel's correction is the factor variance expectation
values of the sample variance ,
(1)
where
(2)
As noted by Kenney and Keeping (1951, p. 161), the correction factor is probably more properly attributed to Gauss, who used it in this connection as early as 1823 (Gauss 1823).
For two samples,
(3)
(Kenney and Keeping 1951, p. 162).
See also Sample Variance ,
Variance
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References Farebrother, R. W. Fitting Linear Relationships: A History of the Calculus of Observations 1750-1900. Gauss, C. F. "Theoria combinationis
obsevationum erroribus minimis obnoxiae." Werke, Vol. 4. Göttingen,
Germany: p. 1, 1823. Kenney, J. F. and Keeping, E. S.
Mathematics
of Statistics, Pt. 2, 2nd ed. Referenced
on Wolfram|Alpha Bessel's Correction
Cite this as:
Weisstein, Eric W. "Bessel's Correction."
From MathWorld https://mathworld.wolfram.com/BesselsCorrection.html
Subject classifications
in the relationship between the variance 
and the expectation
values of the sample variance,
