# CI for StDve in Excel

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• #53344

Örtlund
Participant

Hello

Does anyone know the commando for calculating CI for StDve in excel?

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#189693

Participant

Did you check out MS excel’s helpfile? This is what MS states…

The CONFIDENCE(alpha, sigma, n) function returns a value that you can use to construct a confidence interval for a population mean. The confidence interval is a range of values that are centered at a known sample mean. Observations in the sample are assumed to come from a normal distribution with known standard deviation, sigma, and the number of observations in the sample is n.

SYNTAX

CONFIDENCE(alpha,sigma,n)

Parameters: Alpha is a probability and 0 < alpha < 1. Sigma is a positive number, and n is a positive integer that corresponds to the sample size.

Typically, alpha is a small probability, such as 0.05.

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#189696

Örtlund
Participant

Yes, thats for the population mean,
What I am looking for if there is a comand/function to calculate CI for the StDev (sigma)?

0
#189698

Participant

Computing the Ci of a SD with Excel

These Excel equations compute the confidence interval of a SD. N is sample size; alpha is 0.05 for 95% confidence, 0.01 for 99% confidence, etc.:

Lower limit: =SD*SQRT((N-1)/CHIINV((alpha/2), N-1))

Upper limit: =SD*SQRT((N-1)/CHIINV(1-(alpha/2), N-1))

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#189699

Örtlund
Participant

Thanks a lot!
So there are probably non direct commands then?
O well, This will do the work also.
:)

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