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7.8

Biased/unbiased Standard Deviation

Asked by prashant_n_mhatre in Math & Science, Probability & Statistics

Tags: deviation, standard, unbiased, biased

In standard deviation formula we sometimes divide by (N) and sometimes (N-1)
where N = number of data points.

Somewhere I read that 'N' or 'N-1' does not make difference for large datasets.
but when we calculate std. dev. for less than 20 data points, dividing by 'N' gives
a biased estimate and 'N-1' gives unbiased estimate.

Can someone explain with example..how does subtracting 1 help?
[+][-]06/19/02 06:45 AM, ID: 7092624Accepted Solution

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Zones: Math & Science, Probability & Statistics
Tags: deviation, standard, unbiased, biased
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Solution Provided By: gd2000
Participating Experts: 2
Solution Grade: A
 
[+][-]06/14/02 09:17 PM, ID: 7080054Expert Comment

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[+][-]06/18/02 08:38 AM, ID: 7089880Expert Comment

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[+][-]06/18/02 03:33 PM, ID: 7091078Author Comment

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[+][-]07/02/02 04:51 AM, ID: 7124388Author Comment

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