TRIMMEAN

See Also

Returns the mean of the interior of a data set. TRIMMEAN calculates the mean taken by excluding a percentage of data points from the top and bottom tails of a data set. You can use this function when you wish to exclude outlying data from your analysis.

Syntax

TRIMMEAN(array,percent)

Array is the array or range of values to trim and average.

Percent is the fractional number of data points to exclude from the calculation. For example, if percent = 0.2, 4 points are trimmed from a data set of 20 points (20 x 0.2), 2 from the top and 2 from the bottom of the set.

Remarks

If percent < 0 or percent > 1, TRIMMEAN returns the #NUM! error value.
TRIMMEAN rounds the number of excluded data points down to the nearest multiple of 2. If percent = 0.1, 10 percent of 30 data points equals 3 points. For symmetry, TRIMMEAN excludes a single value from the top and bottom of the data set.

Example

The example may be easier to understand if you copy it to a blank spreadsheet.

How?

Create a blank spreadsheet.
Select the example in the Help topic.

Selecting an example from Help
Press CTRL+C.
In the spreadsheet, select cell A1, and press CTRL+V.
To switch between viewing the formula that returns the result and the result in the cell, select the cell and press F2 and then ENTER, or click Commands and Options on the spreadsheet toolbar, click the Formula tab, and look in the Formula in active cell (active cell) box.

Data
4
5
6
7
2
3
4
5
1
2
3
Formula	Description (Result)
=TRIMMEAN(A2:A12,0.2)	Mean of the interior of a data set above, with 20 percent excluded from calculation (3.777778)