To calculate the trimmed mean from a box and whisker plot, you need to know the minimum, maximum, and median values of the data. Here is the process for calculating the trimmed mean:
- Determine the number of data points that you want to exclude from the mean calculation, called the “trim value.” For example, if you want to exclude the lowest and highest 10% of the data, the trim value would be 20%.
- Calculate the number of data points to exclude by multiplying the trim value by the total number of data points and dividing by 100. For example, if there are 100 data points and the trim value is 20%, you would exclude (20/100) * 100 = 20 data points.
- Sort the data from smallest to largest.
- Exclude the lowest and highest data points equal to the number calculated in step 2. For example, if you have 100 data points and want to exclude the lowest and highest 20 data points, you would exclude the lowest 20 and highest 20 data points, leaving 60 data points for the mean calculation.
- Calculate the mean of the remaining data points using the standard formula: (sum of data points) / (number of data points).
The trimmed mean is a measure of central tendency that is similar to the mean, but it is less sensitive to extreme values or outliers in the data. Trimming a small percentage of the data can help to reduce the influence of outliers on the mean, resulting in a more representative measure of the central tendency of the data.
See also: Winsorized mean
