two sets of data can have a similar mean, mode and median but contain completely different values.

the spread of a set of data can be measured using the range, quartiles, percentiles, variance and the standard deviation.

Key Skills

find the range, quartiles and percentiles of a set of unsorted data

  • calculate the standard deviation of a set of data or frequency distribution using formulae, calculator or spreadsheet.


rangequartilesupper quartilelower quartile, percentilesvariance,standard deviationmedianinterquartile rangedatafrequency,spreadsheetpopulationdenominator.