Section 4-8 Box and Whisker Plots

A Box and Whisker plot can be used to graphically represent a set of data points Box whiskers

Parts of a Box and Whisker plot

The range of a set of data is the difference between the greatest and the least values in the data set Least 15 Greatest 63 Range: 63 – 15 =

Quartiles are the values in a set that separate the data into four sections, each containing 25% or one quarter of the data Lower quartile Q 1 is the median of the lower half of the data Upper quartile Q 3 is the median of the upper half of the data The median quartile Q 2 Separates the data Into two halves

1.) Given the data points 5, 2, 16, 9, 13, 7, and 10 plot the data as a box and whisker plot Arrange data from least to greatest 2, 5, 7, 9, 10, 13, 16 Now find the median

1.) continued 2, 5, 7, 9, 10, 13, and 16 Now find the least and greatest data points Now find the midpoint of the lower half 2, 5, 7, 9, 10, 13, and 16 And the midpoint of the upper half

1.) continued Now plot the points above the number line

1.) continued Now draw a box to designate the interquartile range from Q 1 t o Q 3 mark the median by drawing a segment through the point in the box

1.) continued Now add segments (whiskers) connecting the lower quartile to the least value and the upper quartile to the greatest value

Def: An outlier is any data point in a set of data that is extreme 15, 21, 34, 35, 37, 39, 42, 44, 50, 112 outlier Which of these points is not like the others, Which of these points doesn’t belong?

Homework Page 240 Problems: 7, all