Confidence intervals

One Sample Interval for the Variance and Standard deviation (Χ2 S2-Int)

Confidence intervals for a population variance σ2 and standard deviation σ.
Population must be Normal.

sample size n:
sample standard deviation s:


df=


There is a CL% chance that Var:[,] contains the true σ2 and SD:[,] contains the true σ.
NB. "margin of Error" E does not exist for this situation and s will not be in the exact middle of the confidence interval.

C.L. α α/2 (right) 1-α/2 (left)
90% .1 .05 .95
95% .05 .025 .975
98% .02 .01 .99
99% .01 .005 .995
XL2 = X2table[df][1-α/2]
XR2 = X2table[df][α/2]

Χ2 table

More about Χ2