1. A Box and Whisker What??? A detailed guide to making and interpreting Box and Whisker Plots. Mrs. C. Fisher – Whetstone Elementary

2. Box and Whisker Plots Box and Whisker Plots are a method used to analyze a given set of data. Let’s use some pretend math scores as a sample data set: 77,81, 83, 85, 85, 86, 86, 87, 89, 90, 93, 93, 97, 100 We must first identify the median of the data set. Remember that the median is the middle number when the data set is ordered from least to greatest. If there is an even number of numbers in the data set, then we must find the mean of the two middle numbers. Step 1: Find the Median

3. 77,81, 83, 85, 85, 86, 86, 87, 89, 90, 93, 93, 97, 100 There are 14 numbers so there is no true middle number! 86 and 87 are the two middle numbers. What is their mean. 86 + 87 = 173173 divided by 2 is 86.5…..The Median

4. 77,81, 83, 85, 85, 86, 86, 87, 89, 90, 93, 93, 97, 100 Step 1: Find the Median Step 2: Find the Upper and Lower Extreme This step is easy. The Upper and Lower Extremes are simply the smallest and largest numbers in the data set. In our example: 77 and 100 Lower Extreme Upper Extreme Not those whiskers, silly!!

5. Step 1: Find the Median 77,81, 83, 85, 85, 86, 86, 87, 89, 90, 93, 93, 97, 100 Step 2: Find the Upper and Lower Extreme Step 3: Find the Upper and Lower Quartile The Upper Quartile is simply the median of the upper half of the data set. The Lower Quartile is the median of the lower half of the data set. Median 86.5 Lower Extreme Upper Extreme Lower Quartile: 85 Upper Quartile 93

6. Put It All Together Lower Extreme: 77 Lower Quartile: 85 Median: 86.5 Upper Quartile: 93 Upper Extreme: 100 Create a number line that spans the set of data: for our example 70-100 7075858090 95 100 Place a vertical line above the Quartiles and Median. Place a point above the Extremes. Connect the vertical lines with horizontal lines to make a rectangle/box. Draw a line from the box to the Extremes ٠٠

7. 707580859095100 You’re Done!! Analysis: When analyzing Box and Whisker Plots, it is common to discussing Quartiles (fourths) or percents. 50 % of students did better than 86.5 The top 25% of students scored about 93 or higher