Quartiles, spread and standard deviation

What this note covers

1. Why two data sets with the same average can be nothing alike
2. Range: quick, useful, and easily wrecked
3. Quartiles, the interquartile range and the five-number summary
4. Percentiles and quantile intervals
5. Cumulative frequency tables and curves
6. Standard deviation: what your calculator is doing
7. Choosing between the measures and comparing groups

7 sections · 12 key terms & formulas · 6 common mistakes