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Statistical function
TRIMMEAN
Returns the mean after excluding a percentage of the highest and lowest values.
OccasionalDifficulty 1300 · ProficientUsage rank #205 of 520
When to use it
The mean after removing a percentage of the data from each end. A robust average that drops outliers symmetrically.
The shape of it
- Syntax
=TRIMMEAN(array, percent)
Worked examples
Drop one from each end
=TRIMMEAN({1,2,3,4,5,6,7,8,9,100},0.2) → 5.5
20% of ten points is two, one from each end. Mean of 2 to 9.
Trim 10% overall
=TRIMMEAN(B2:B101,0.1) → 51,800
Salaries with the top and bottom 5% removed.
No trim
=TRIMMEAN(B2:B101,0) → 54,300
No trimming; the same as AVERAGE.
Worth knowing
- Percent is the total removed, split between the two ends and rounded down to a multiple of two.
- Olympic-style scoring is TRIMMEAN with 2/n.
- Compare with MEDIAN to see how much the tails matter.
Where it goes wrong
- #NUM! when percent is outside 0 to 1.
- Small samples may trim nothing because the count rounds to zero.
Related
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