STAT 2230 Lecture Notes - Lecture 2: Quartile, Box Plot
17 Dec 2015
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Document Summary
Skew occurs with a lot more values above or below the means (unbalanced distributions) Mean and median provide two different measures of the center of a distribution. Simplest useful numerical description of a distribution requires measure of center and measure of spread. Quartiles mark out the middle half: first quartile lies one quarter of the way up the list and third quartile is three quarters up the list. To calculate quartiles, arrange observations in increasing order and locate the median. Descriptive stats page 1 order and locate the median. Q1 is median of observations to the left of the median. Q3 is median of observations to the right of the median. This distance is a much more resistant measure of spread. Numbers are considered outliers if it falls more than 1. 5 x iqr above q3 or below q1. Includes minimum, q1, median, q3 and maximum numbers. Offer a reasonable description of center and spread.
