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A Box and Whisker What???

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

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A Box and Whisker What???

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  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 Step 1: Find the Median 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.

  3. There are 14 numbers so there is no true middle number! 77,81, 83, 85, 85, 86, 86, 87, 89, 90, 93, 93, 97, 100 86 and 87 are the two middle numbers. What is their mean. 86 + 87 = 173 173 divided by 2 is 86.5…..The Median

  4. Not those whiskers, silly!! Lower Extreme Upper Extreme 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

  5. Upper Quartile 93 Lower Quartile: 85 Median 86.5 77,81, 83, 85, 85, 86, 86, 87, 89, 90, 93, 93, 97, 100 Upper Extreme Lower Extreme Step 1: Find the Median 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.

  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 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 ٠ ٠ 70 75 80 85 90 100 95

  7. 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 70 75 80 85 90 95 100

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