Читать книгу Statistics and Probability with Applications for Engineers and Scientists Using MINITAB, R and JMP - Bhisham C. Gupta, Irwin Guttman - Страница 91

This section introduces measures of relative position that divide the data into percentages to help locate any data value in the whole data set. Commonly used measures of relative position are percentiles and quartiles: percentiles divide the data into one hundred parts, such that each part contains at the most 1% of the data, and quartiles divide the data into four parts, such that each part contains at the most 25% of the data. Then from quartiles, we can derive another measure, which is called the interquartile range (IQR), to give the range of the middle 50% of the data values. This is obtained by first organizing the data in an ascending order and then trimming 25% of the data values from the lower and the upper ends. A quantile is a value which divide a distribution or an ordered sample such that a specified proportion of observations fall below that value. For instance, the percentiles and quartiles are very specific quantiles.