Transcript box-and-whisker plot

You have already found measures of central
tendency. (Lesson 13–2)
• Find measures of variation.
• Display data in a box-and-whisker plot.
• Measures of variation – used to describe the
distribution of statistical data
• box-and-whisker plot – a diagram that divides
a set of data into four parts using the median
and quartiles
• box = the quartile values
• whiskers = extend to the extreme data points
Outliers = greater than or less than the IR • 1.5
Find Outliers
NUTRITION Find any
outliers in the data set.
Step 1 Place the numbers in
order from least to greatest
and find the median, lower
quartile and upper quartile
lower quartile median
2.5
3
3
4.5
5
upper quartile
5
6
8
14
Median: 5
Lower quartile:
Upper quartile:
Find Outliers
NUTRITION Find any
outliers in the data set.
Step 2 Find the
interquartile range.
Interquartile range = UQ – LQ = 7 – 3 = 4.
Step 3 Multiply the interquartile range by 1.5.
1.5 ● 4 = 6
Step 4 Subtract 6 from the lower quartile and add 6 to
the upper quartile.
3 – 6 = –3
7 + 6 = 13
Answer: The only outlier is 14 because it is greater
than 13.
Draw a Box-and-Whisker Plot
JOBS The projected number
of employees in 2010 in the
fastest-growing occupations is
shown. Display the data in a
box-and-whisker plot.
Step 1 Find the least and
greatest number. Then
draw a number line that
covers the range of the
data.
Draw a Box-and-Whisker Plot
Step 2
Find the median, the extremes, and the
upper and lower quartiles. Mark these points
above the number line.
Draw a Box-and-Whisker Plot
Step 3
Answer:
Draw the box and the whiskers.