TRIMMEAN
TheTRIMMEAN
function calculates the mean of a given data set after trimming a proportion of the data points from both the top and bottom of the set. This function is commonly used to calculate the central tendency of a data set while excluding outliers. The proportion of data points to be excluded can be specified as a decimal or percentage value.
 How to use
TRIMMEAN
formula?  Examples of using
TRIMMEAN
formula TRIMMEAN
formula not working? Similar formulas to
TRIMMEAN
Usage
Use the TRIMMEAN
formula with the syntax shown below, it has 2 required parameters:
 data (required):
The range or array of values from which to calculate the trimmed mean. The data set must contain at least three values.  exclude_proportion (required):
The proportion of data points to exclude from both the top and bottom of the data set. This can be specified as a decimal or percentage value.
Examples
Here are a few example use cases that explain how to use theTRIMMEAN
formula in Google Sheets.
Calculating the average grade
A teacher wants to calculate the average grade for a class of 30 students, but wants to exclude the top and bottom 10% of grades to account for outliers. The TRIMMEAN
function can be used to calculate the trimmed mean of the grades.
Calculating the average temperature
A weather forecaster wants to calculate the average temperature for a month, but wants to exclude the unusually high and low temperatures to get a more accurate value. The TRIMMEAN
function can be used to calculate the trimmed mean of the temperatures.
Calculating the average sales
A sales manager wants to calculate the average sales for a team of 20 sales representatives, but wants to exclude the top and bottom 20% of sales to account for outliers. The TRIMMEAN
function can be used to calculate the trimmed mean of the sales.
Common Mistakes
TRIMMEAN
not working? Here are some common mistakes people make when using the TRIMMEAN
Google Sheets Formula:
Not providing a range or array for the data parameter
If no data range or array is provided for the data parameter, the TRIMMEAN function will return an error.
Providing a value outside of the 01 range for the exclude_proportion parameter
The exclude_proportion parameter should be a decimal value between 0 and 1. If a value outside of this range is provided, the TRIMMEAN function will return an error.
Related Formulas
The following functions are similar to TRIMMEAN
or are often used with it in a formula:

AVERAGE
The AVERAGE function calculates the average (arithmetic mean) of the values passed to it. It is commonly used to find the average of a range of cells containing numerical data.

MEDIAN
The
MEDIAN
function returns the median (middle) value of a set of numbers. It is commonly used to find the middle value in a range of data points. If the number of data points is even, it returns the average of the two middle values. This function can be useful in statistical analysis and data visualization. 
MODE
The MODE formula in Google Sheets returns the most frequently occurring value in a dataset. It is commonly used in statistical analysis to identify the value that occurs most frequently in a set of data. The formula requires at least one input value, but can accept multiple values to include in the analysis.

STDEV
The
STDEV
function calculates the standard deviation of a set of numbers. It measures the amount of variation or dispersion of a set of values from the average (mean) value. It is commonly used in statistics to determine the spread of a data set. The values can be supplied as individual cells, ranges, or constants. 
PERCENTILE
The
PERCENTILE
function returns the value at a given percentile of a dataset. This can be useful in statistics and data analysis when trying to find the value that corresponds to a certain percentile in a set of data.
Learn More
You can learn more about the TRIMMEAN
Google Sheets function on Google Support.