In Google Sheets, the TRIMMEAN function is used to calculate the trimmed mean of a range of values.

The trimmed mean is a statistical measure that calculates the average of a dataset after excluding a certain proportion of the highest and lowest values.

The TRIMMEAN function has two arguments:

data: This is the range of values for which you want to calculate the trimmed mean. It can be a range of cells or an array of values.

exclude_proportion: This is the proportion of values you want to exclude from the calculation. It should be specified as a decimal between 0 and 1.

For example, if you want to exclude the highest and lowest 10% of values, you would enter 0.1 as the exclude_proportion.

The formula for using the TRIMMEAN function in Google Sheets is:

=TRIMMEAN(data, exclude_proportion)

Here's an example to illustrate how the TRIMMEAN function works:

Suppose you have a range of values in cells A1 to A10, and you want to calculate the trimmed mean excluding the highest and lowest 20% of values. The formula would be:

=TRIMMEAN(A1:A10, 0.2)

This will return the trimmed mean of the values in the range A1 to A10, after excluding the highest and lowest 20% of values.