Читать книгу Statistics - David W. Scott - Страница 8

Tukey (1977) introduced a number of data summaries in his book Exploratory Data Analysis. Many are based on quantiles or percentiles of the data vector. Percentiles are particular choices of the sorted data. The middlemost is the median, or the 50th percentile. As a measure of spread, Tukey focused on the distance from the 25th to the 75th percentiles, the so‐called interquartile range (IQR). A three‐point summary would list these percentiles. Instead Tukey popularized the box‐and‐whiskers plot, which is a five‐point summary. The additional two points are intended to capture 99% of the data. These are drawn at a distance of from the two quartiles. Any points outside these whiskers are plotted as potential outliers.