Author: Oscar Cronquist Article last updated on June 20, 2018

The TRIMMEAN function calculates the mean of the interior of a data set. The function excludes a percentage of data points from the top and bottom tails of a data set, use it to exclude outlying data from your analysis.

Formula in cell D3:

=TRIMMEAN(B3:B12,0.4)

40 % of the data points in cell range B3:B12 are excluded from the calculation.

Excel Function Syntax

TRIMMEAN(array, percent)

Arguments

array Required. The values to trim and average.
percent Required. The fractional number of data points to exclude from the calculation. If percent is 0.2 and there are 100 data points, 20 data points are excluded.

Comments

The TRIMMEAN function rounds the number of excluded data points to the nearest multiple of 2 to create symmetry and exclude the same number of data points from top and bottom.

Example, if there are 100 data points and the percentage is 0.01 then 2 values are excluded even though 0.01 * 100 = 1.