Confidence Intervals 

Confidence intervals are calculated as:

where

• is the average value of the group

• s is the sample standard deviation

• n is the number of values in the group (Count)

The L95 value is the lower endpoint of the confidence interval.

The U95 value is the upper endpoint of the confidence interval.

Note: The static t-value of 1.959964, used by the L95 and U95 functions, is adapted for large sample sizes (n >= 40). For smaller sample sizes, use the following custom expressions instead:

L95: Avg([Value])-TInv(0.025,Count()-1)*StdDev([Value])/Sqrt(Count())

U95: Avg([Value])+TInv(0.025,Count()-1)*StdDev([Value])/Sqrt(Count())