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In descriptive statistics, the interquartile range (IQR), also called the midspread or middle fifty, is a measure of statistical dispersion, being equal to the difference between the upper and lower quartiles,〔〔 IQR = ''Q''3 − ''Q''1. In other words, the IQR is the 1st quartile subtracted from the 3rd quartile; these quartiles can be clearly seen on a box plot on the data. It is a trimmed estimator, defined as the 25% trimmed range, and is the most significant basic robust measure of scale. ==Use== Unlike total range, the interquartile range has a breakdown point of 50%, and is thus often preferred to the total range. The IQR is used to build box plots, simple graphical representations of a probability distribution. For a symmetric distribution (where the median equals the midhinge, the average of the first and third quartiles), half the IQR equals the median absolute deviation (MAD). The median is the corresponding measure of central tendency. Identification of outliers (see below). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「interquartile range」の詳細全文を読む スポンサード リンク
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