Median

1. The median length of sentence is the mid-point of the set. So, putting them in order, we have:

14, 15, 16, 16, 16, 17, 18

The median is therefore 16 months (the fourth value in the list of seven).

2. Adding in a five year sentence (60 months), the ranking now becomes:

14, 15, 16, 16, 16, 17, 18, 60

The median is now the mean of the fourth and fifth values in the list (since there is now an even number of values). It is the mean of 16 and 16 – which is, again, 16 months. This compares to a mean of 21.5 months. The median is therefore not greatly distorted by the addition of the ‘extreme’ sentence, so it is a more representative view of the overall characteristics of the distribution.