Returns the mean of the interior of a data set by excluding a specified percentage of data points from the top and bottom tails.
This function works the same in Google Sheets as it does in Excel — same syntax and arguments.
TRIMMEAN(array, percent)TRIMMEAN calculates the average of a data set after removing a specific percentage of outliers from both the top and bottom ends. This function is useful for eliminating extreme values that might skew the overall average of a distribution.
=TRIMMEAN({1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, 0.2)Result: 5.5
Excludes 20% of 10 values (2 values total, 1 from each end), averaging the remaining 8 values (2 through 9).
It rounds the number of excluded points down to the nearest multiple of 2.