The interquartile mean (IQM) (or midmean) is a statistical measure of central tendency based on the truncated mean of the interquartile range. The IQM is very similar to the scoring method used in sports that are evaluated by a panel of judges: discard the lowest and the highest scores; calculate the mean value of the remaining scores.

In calculation of the IQM, only the data between the first and third quartiles is used, and the lowest 25% and the highest 25% of the data are discarded.

assuming the values have been ordered.

The method is best explained with an example. Consider the following dataset:

First sort the list from lowest-to-highest:

There are 12 observations (datapoints) in the dataset, thus we have 4 quartiles of 3 numbers. Discard the lowest and the highest 3 values:

We now have 6 of the 12 observations remaining; next, we calculate the arithmetic mean of these numbers:

This is the interquartile mean.