The trimean is an estimate of central tendency, and is calculated as a weighted average of the median and the two quartiles of a set of values.

The formula for trimean is (quartile1 + median * 2 + quartile3) / 4. Trimean is considered a robust statistic, and is therefore less sensitive to outliers in the data.

Example

Given the values [5,10,15,20], the statistics are:

• Quartile1 = 7.5 = (5 + 10) / 2
• Median = 12.5 = (10 + 15) / 2
• Quartile3 = 17.5 = (15 + 20) / 2
• Trimean = 12.5 = (7.5 + 12.5 + 12.5 + 17.5) / 4