2I can organize and display data in a box and whisker plot. Course 3I can organize and display data in a box and whisker plot.I can determine the upper and lower extremes, median, and upper and lower quartiles in a box plot.
3Box and Whisker PlotsWhen we are working with a larger set of data it is much easier to separate the data into quartiles. The quartiles separate the data into four equally sized parts.There are five important values to remember if you want to divide your data into quartiles:Lower QuartileUpper QuartileMedianLowest ValueHighest Value
4Box and Whisker Plots The lower extreme is the lowest value The upper extreme is the highest valueThe median is the middle numberThe lower quartile divides the lower ½ of the data into two equally sized groupsThe upper quartile separates the upper ½ into two equally sized groupsLower QuartileUpper QuartileMedianLowest ValueHighest Value
5Box and Whisker PlotsThe difference between the lower quartile and the upper quartile is called the interquartile range and corresponds to the 50% of the data points that are in the middleLower QuartileUpper QuartileMedianLowest ValueHighest Value
6To draw a box-and-whiskers plot begin by marking the five numbers described on the previous slides with dots:
7The next step is to draw the box The next step is to draw the box. The box has its sides at the LQ and the UQ and we display the median by drawing a line.Then we extend the whiskers from each quartile to the upper and lower extremes.This box-and-whiskers plot separates the data into quarters (called quartiles) with the same number of data points in each part:Quartiles
8Litter Size Number of Litters Practice finding the values:The table below summarizes a veterinarian’s records for kitten litters born in a given year.Litter Size23456Number of Litters1811Writing the data out would look like this:2,3,3,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,6
9Kitten DataThe range of a data set is the largest value minus the smallest value. For the kitten data, the range is 6 — 2 = 4.Lower halfUpper halflower quartile: 3Median: 4 (second quartile)upper quartile: 5 median of upper halfLitter Size23456Number of Litters1811(1st part) (2nd Part) (3rd part) (4th Part)Course 3
10Making a Box and Whisker Plot - Practice Step 1: Find the lower extreme, lower quartile, median, upper quartile, and upper extreme:21, 25, 15, 13, 17, 19, 19, 21Order the values.lower extreme: 13lower quartile: 15What would the interquartile range be?21 – 15 = 6median: 19upper quartile: 21upper extreme: 25
11Making a Box and Whisker Plot Course 39-4VariabilityMaking a Box and Whisker PlotStep 2: draw a number line and plot a point above each value from Step 1.Lower extreme13lower quartile 15median19upper quartile 21Upper extreme25
12Making a Box and Whisker Plot Course 39-4VariabilityMaking a Box and Whisker PlotStep 3: Draw the box and whiskers:
13ComparingFinal1234TOakland61221Tampa Bay171448OaklandTampa BayWhen data is displayed in a box and whisker plot you can visually compare the information given. It is very easy to see the five important numbers that make up a box and whisker plot.
14Compare the medians:OaklandTampa BayThe median for Tampa Bay is significantly greater.
15Compare the differences between the upper quartile and lower quartile for each: OaklandTampa BayThe difference between the upper quartile and lower quartile is the length of the box, which is slightly greater for Oakland.
16You Try:1. Organize the given data into a box and whisker plot:The number of fish caught each day for nine days straight is 26, 17, 21, 23, 19, 28, 17, 20, and 292. Organize the given data into a box and whisker plot.The number of pizzas needed for each class is 6, 10, 7, 12, 9, 10, and 11Find the interquartile range for each