Quartiles Box and Whisker Plots Quartiles n Step
Quartiles + Box and Whisker Plots
Quartiles n Step 1: Find the Median. This is called Q 2, or the second quartile. n Step 2: Split the first half into 2 equal groups (same rules as finding the median). The middle value is called Q 1, or the first quartile. n Step (Q 3). n You 3: Find median of top half of numbers have split the numbers into 4 quarters.
n 12, 15, 18, 24, 26, 29, 30, 32 Q 2 = average of 24 and 26 Q 2 = 25
n 12, 15, 18, 24, 26, 29, 30, 32 Q 2 = 25 Q 1 = 16. 5 Q 3 = 29. 5
Box and Whisker Plot n 1) Draw a number line from the lowest to highest value 10 32 n 2) 12 14 16 18 20 22 24 26 Draw a line above Q 1, Q 2 and Q 3 28 30
Box and Whisker Plot 10 32 12 n 2)Draw n 3) 14 16 18 20 22 24 26 a line above Q 1, Q 2 and Q 3 Attach lines to make the “box” 28 30
Box and Whisker Plot 10 32 12 14 16 18 20 22 24 26 n 2) Draw a line above Q 1, Q 2 and Q 3 n 3) Attach lines to make the “box” 28 30
Box and Whisker Plot 10 32 12 14 16 18 20 22 24 26 28 30 n 4) Draw a line over the minimum and maximum values n 5) Draw “whiskers”
Example n 6, 8, 12, 14, 17, 19, 21, 24, 25 Q 2 Q 1 = 10 Q 3 = 22. 5
Measures of Dispersion n Variation Interval: [Xmin , Xmax] 100% of data in this interval n Range: Xmax – Xmin n Interquartile Interval: [Q 1, Q 3] 50% of data in this interval n Interquartile Range: Q 3 – Q 1
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