1. Microsoft Clip Art
C HAPTER 9: D ATA AND
S TATISTICS

2. O RGANIZING D ATA
 Data from surveys can be organized in multiple
ways:
 Line Plot
 Stem-and-Leaf Plot
 Back-to-Back Stem-and-Leaf Plot
 Venn Diagram

3. L INE P LOT
 A line plot uses a number line to organize the data
from a survey.
 The line plot shows how often the numbers in the
data set occur.
 An “x” is placed above the number on the number
line every time that value occurs in the data set.
There were 21 numbers in
this data set. Each “x”
represents one number

4. S TEM - AND -L EAF P LOT
 A stem and leaf plot organizes and displays data to
compare frequencies, or how often the numbers
occur.
 Each leaf represents the right-hand digit in the
value, or ones place.
 Each stem represents the left-hand digit in the
value, or tens place.

5. S TEM - AND -L EAF P LOT
C ONT ’
 Reading Stem and Leaf Plots
 Example:
The leaves should be
written in order
A key needs to be
included to explain how
to read the numbers
 The values are
4, 6, 12,13, 15, 20, 25, 29, 38, 41, 44, 46, 47, 49

6. B ACK - TO -B ACK S TEM - AND -
L EAF P LOTS
 Back-to-back stem-and-leaf plots can be used to
compare two sets of data.
 The stems are listed in the center, and the leaves
are listed on the right and left sides of the plot.
 The left side leaves are read in reverse.
 A key needs to be used to explain how the
numbers should be read.
Microsoft Clip Art

7. B ACK - TO -B ACK S TEM - AND -
L EAF P LOTS C ONT ’
 Example: Use the given data to make a back-to-
back stem-and-leaf plot.
Animal Endangered Threatened
Mammals 60 8
Birds 76 15
Reptiles 16 47
Amphibians 10 7
Fish 72 43
Be sure to include a
The left side leaves are read in key to explain how the
reverse and written in order from numbers should be
biggest to smallest. read!

8. V ENN D IAGRAMS
 Venn diagrams are used to compare sets of data.
 Example: Make a Venn diagram to show how many
sixth grade students have an iPod and a computer.
iPod Yes Yes No Yes No No No Yes
Computer No Yes Yes Yes No Yes Yes No
These students ONLY have a
These students ONLY computer
have an iPod
The number in the lower
right hand corner
represents the students
The overlap section
who have neither an iPod
represents students who have
nor a computer.
both an iPod and a computer.

9. M EASURES OF C ENTRAL
T ENDENCY
 Mean: To find the mean, add up all the numbers
in the data set and then divide by the number of
values in the set (also called the average).
 Median: The middle number in a set of data. If
there is an even number of values in the data
set, the median is found by taking the mean of
the two middle values.
 Mode: The number that occurs most frequently.
 Range: The difference between the highest and
lowest values in a set of data.
Microsoft Clip Art

10. M EASURES OF C ENTRAL
T ENDENCY CONT ’
 Example: Find the mean, median, mode, and
range of the following data set.
2, 4, 4, 5, 7, 7, 7, 9, 9

11. VARIABILITY AND B OX AND
W HISKER P LOTS
 Variability: describes how spread out the data is
 Quartiles: divides the data into four equal parts
 Box and whisker plot: shows how the data is
distributed
 Example: Find the first and third quartiles of the
data

12. B OX AND W HISKER P LOTS
 Box and whisker plots show the distribution of
data
 The middle half of data is the “box” with a line at
the median.
 The lower fourth and upper fourth of data are
the “whiskers.”
Microsoft Clip Art

13. B OX AND W HISKER P LOTS
C ONT ’
 Example: Use the given data to make a box and
whisker plot
1 1 3 3 4 5 6 6 8 8 9 9 9 10
 Step 1: Find the smallest value, largest value, first
quartile, median, and third quartile

14. B OX AND W HISKER P LOTS
C ONT ’
 Step 2: Draw a number line. Plot a point above
each value from the previous step.
 Step 3: Draw the box and whiskers.

15. D ISPLAYING D ATA
 Data can be displayed using a variety of graphs.
 Double bar graph
 Histogram
 Double line graph
 Scatter plot
Microsoft Clip Art

16. D OUBLE B AR G RAPHS
 Double bar graphs are used to show a comparison
between two sets of data.
 Example: Make a double bar graph with the following
data
 The data below shows the ages of boys and girls
playing on little league baseball teams.
Age 6 7 8 9 10 11
Boys 7 6 3 0 10 15
Girls 5 6 8 2 9 14

17. D OUBLE B AR G RAPHS C ONT ’
Every graph must
have a title!
A key must be
The x-axis and included to show
y-axis must what each colored
have labels! bar represents

18. H ISTOGRAMS
 Histograms are bar graphs that show the frequency of
data within equal intervals.
 Example: Make a histogram with the following data
 The following data shows the average high
temperatures of tourist cities in April. Create a
histograms using intervals of 10.
Average High Temperatures in April in Tourist Cities
Acapulco, Mexico 86 Montreal, Canada 52
Athens, Greece 68 Nassau, Bahamas 82
Dublin, Ireland 53 Paris, France 61
Hong Kong, China 78 Rome, Italy 70
London, U.K. 57 Sydney, Australia 71

19. H ISTOGRAMS C ONT ’
 Use a frequency table to organize the data
 List the items from the previous table according
to the number of times the items occur.
Interval (Temperatures) Frequency
50 – 59 3
60 – 69 2
70 – 79 3
80 - 89 2

20. H ISTOGRAMS C ONT ’
Remember to
include a title!
The x-axis and
**There are no spaces
y-axis must between the bars in a
have labels! histogram!**

21. D OUBLE L INE G RAPHS
 Double line graphs show a comparison of two
sets of data over time.
 Example: Create a double line graph with the
data below to compare the number of radio
stations and television stations.
Year Radio Stations Television Stations
1997 9,105 10,800
1999 9,500 10,430
2001 10,100 9,875
2003 10,350 9,430

22. D OUBLE L INE G RAPHS
C ONT ’
Include a
title and
labels for
each axis
Label! Include a key to
explain each data set

23. S CATTER P LOTS
 Scatter plots are graphs that show plotted points to
show a relationship between two sets of data.
 If the points on a scatter plot are close together, a line
of best fit can be drawn.
 A correlation describes the relationship between the
two sets of data.
 A scatter plot can have a positive correlation, negative
correlation, or no correlation.

24. S CATTER P LOTS C ONT ’
 Example: Create a scatter plot with the following data
Calories and Fat Per Portion of Meat Remember to title your graph!
Fat (grams) Calories
Breaded Fish Sticks 4 52
Fried Shrimp 8 191
Tuna 7 168
Ground Beef 11 185
Roast Beef 6 163
Ham 19 249
Include labels for the x-axis and y-axis

25. S UMMARY
 Data can be organized using line plots, stem-
and-leaf plots, and Venn diagrams.
 Measures of central tendency include
mean, median, mode, and range.
 Distribution of data can be shown using a box
and whisker plot.
Microsoft Clip Art  Data can be displayed on bar
graphs, histograms, line graphs, and scatter plots.
 All graphs MUST include a title and labels!

26. R ESOURCES
 Images created by J. Hirschfield using Microsoft
Paint
 Course Textbook used as a guiding resource
 Bennett, Jennie M., et al. Holt Mathematics:
Course 3. Austin: Holt, Rinehart, and Winston,
2007. Print.