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# WorksheetFunction.TrimMean Method (Excel)

Office 2013

Published: July 16, 2012

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.

expression .TrimMean(Arg1, Arg2)

expression A variable that represents a WorksheetFunction object.

### Parameters

Name

Required/Optional

Data Type

Description

Arg1

Required

Variant

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

Arg2

Required

Double

Percent - 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.

### Return Value

Double

• 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.