Microsoft KB Archive/62823

Works: Correction Factor for Standard Deviation

PSS ID Number: Q62823 Article last modified on 10-16-1998

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MS-DOS

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= SUMMARY =

Many calculators and software packages use a formula that estimates a population standard deviation. Works does not presume that the data is from a sample and that it is being used to estimate a population standard deviation. The number generated by Works can be adjusted for use in statistics by multiplying STD by a factor that is the square root of the sample size divided by the square root of the sample size minus one.

= MORE INFORMATION =

If sample data is used for quality assurance, interval estimates, hypothesis testing, or other statistical work, a correction factor must be used to account for the one degree freedom lost when the sample mean was used to estimate the population mean.

The formula used by Works is as follows:

SQRT(SquaredDeviationsFromMean/SampleSize)

The formula used to calculate an estimated population standard deviation is as follows:

SQRT(SquaredDeviationsFromMean/(SampleSize-1))

If the data is in column B, rows 11 through 30 (20 data points), the following formula will calculate an estimated population standard deviation:

SQRT(20/(20-1))*STD(B11:B30)

The correction factor is the square root of the sample size divided by the square root of the sample size minus 1.

KBCategory: kbother KBSubcategory: dworkskb Additional reference words: ====================================================================== Version : 1.00 1.05 2.00 3.00 Platform : MS-DOS ============================================================================= Copyright Microsoft Corporation 1998.