Summarising data - overview
We are able to collect and analyse data in many situations.
The data might be recorded in a data table and / or a graph to summarise
the range, the concentration and spread of the data. For example, much
weather data for temperatures and rainfall are summarised in tables and
graphs of various types (typically - column, bar and line graphs).
Similarly, much social data regarding such matters as birth rates, life
expectancy, marriage rates, population rates and income distribution is
summarised with tables and graphs.
Typically, when we look at graphs we are interested in the measures of
central tendency of the data - mean (the average), median (the middle
score) and mode (the most popular score) - and the indicators for the
spread of the data - the range and the interquartile range.
Let\'s investigate these quantities - the mean, median, mode, range and
interquartile range - for a number of normal situations for which data has