FUNCTION TRIMMEAN

This function 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.

How does it work?

=TRIMMEAN(array, percent)

The TRIMMEAN function syntax has the following arguments (argument: A value that provides information to an action, an event, a method, a property, a function, or a procedure.):

Where:

Array (Required). The array or range of values to trim and average.

Percent (Required). 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. So, the percentage value should be in between 0 & 1.

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.