Confidence Interval

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

The individual CONFIDENCE() function [CONFIDENCE(alpha, STDEV, n)] returns a
different confidence interval than if you use Descriptive Statistics Analysis
[Tools>Data Analysis>Descriptive Statistics]. In fact, I've been witnessing
a 25% difference between the two values.
Any ideas why these two methods of calculating the confidence interval yield
different results?
 
The CONFIDENCE() function is rarely appropriate, because you rarely know the
population standard deviation. For an estimated standard deviation, you
should use
CONFIDENCE(alpha,S,n)*(-TINV(alpha,n-1)/NORMSINV(alpha/2))
The multiplicative factor which will roughly equal 1.25 when n=7

Jerry
 

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