QMS 102 Lecture Notes - Quartile, Interquartile Range, Empirical Probability
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With no outliers: draw an evenly spaced scale that covers all of the data values, using the scale, draw the box in the 1st and 3rd quartiles as the sides of the box. Join the two vertical sides with horizontal sides to form a box: using the scale as reference, draw a vertical line across the box to represent the median q2. Whichever box contains the average (or mean), draw a plus sign inside that corresponding box: using the scale as reference, draw a horizontal line linking q1 to the minimal value xmin. This line is called the left whisker: using the scale as reference, draw a horizontal line linking q3 to the maximal value xmax. Suspect outliers are defined as data values that lie between the inner and outer fences. They are plotted individually using a special symbol. Outliers are defined as data values that lie outside the outer fences. They are plotted individually using the special symbol *