A data set can be summarised with a measure of centre: the mean, median or mode.
The article on the AAMT website What is 'Typical' for Different Kinds of Data? uses data from Melbourne Cup winners to explore and explain what 'typical' might mean in regards to:
- the mode
- the median
- the mean
- both the median and mean
- using numerical attributes within categorical data.
You can read about the use of measures of centre in context and in the media in What's Average?.
A measure of spread and clusters of data can be used to summarise a data set. In the middle years, spread is usually described with the range of the entire data set. The range of the middle half (50%) of the data is also useful.
Combining the contribution of the median and measures of spread is the box plot created from the five-number summary, which includes the median, maximum and minimum (range), and interquartile range (middle 50% of the data).
The presence of outliers in data sets may influence the measures that summarise a data set.
