ECON 2B03 Lecture Notes - Lecture 6: Royal Institute Of Technology, Interquartile Range, John Tukey
25 Apr 2016
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Lecture 06 - chapter 1 & 2 in textbook. The five number summary of a set of observations consists of the smallest observation, the first quartile, the median, the third quartile, and the largest observation, written in order from smallest to largest. Outliers are troublesome data points, and it is important to be able to identify them. One way to raise the flag for a suspected outlier is to compare the distance from the suspicious data point to the nearest quartile (q1 or q3) We then compare this distance to the interquartile range (distance between q1 and q3) We call an observation a suspected outlier if it falls more than 1. 5 times the size of the interquartile range (iqr) below the first quartile or above the third quartile. This is called the 1. 5 iqr rule for outliers . A box-and-whisker plot (sometimes called simply a box plot") is a histogram-like method of displaying data, invented by john tukey.
