Looking for meaningful variables
Sometimes a simple transformation of the raw data that have been collected provides a variable whose values are more meaningful or highlight a different aspect of the data.
GDP in European countries
European population
Other examples
When a quantity is recorded at different times, it is often useful to analyse its percentage change rather than its raw value. For example, mapping the percentage change in calorie intake per capita of developing countries highlights the countries that are improving.
When the values of imports or exports are reported over a series of years, it is usual to take account of inflation by dividing by a price index (e.g. the consumer price index).
Always think carefully about the variables you have been given. Are they accurate? Are there other variables that would be more informative?