Measures of Spread  
Summary 
the spread of a set of data can be measured using the range, quartiles, percentiles or the standard deviation. the range is the difference between the highest and the lowest values. the percentiles split a set of data into a hundred equal parts. the standard deviation of a set of data is a measure of how each value differs or deviates from the mean. 
Key Skills 

Vocabulary 
spread, quartile, lower quartile, upper quartile, median, mean,percentile, 