- A tenth portion or band of a set of data. A decile is a proportion of a set of data that has been
ranked and divided
into ten groups (or bands), where each group contains an equal number of
For example, consider the (ordered) data set of 20 letters: "A A A B B C D E F G G H I J K L L M N N". The first decile would contain "A A", the second decile "A B", the third "B C" and so on.