Depending on whether the number of observations is even or odd, the median can be estimated as follows:

1. If n = 2 m + 1: The middle value of a series of observations, arranged in increasing or decreasing order.
2. If n = 2 m: The arithmetic mean of the two middle values of a series of observations, arranged in increasing or decreasing order.

Comment: The use of the median when reporting results of chemical analysis is generally not recommended, because its statistical efficiency is less than that of the mean. In certain cases, however, especially when treating small sets of data, the median may offer advantages because it is a so-called 'robust statistic', i.e. it offers considerable resistance to the effects of isolated outliers.