1.1 Analyzing Categorical Data ~ Chapter 1 Pre-Chapter Questions…
Read pages 2 ~ 4
1.
What’s the difference between categorical and quantitative variable?
2.
Do we ever use numbers to describe the values of a categorical variable?
3.
What is a distribution?
4.
Alternate Example: US Census Data
Here is information about 10 randomly selected US residents from the 2000 census.
State
Number of Family Age Gender
Marital
Total Travel Time
Members
Status
Income
To Work
Kentucky
2
61 Female
Married
21000
20
Florida
6
27 Female
Married
21300
20
Wisconsin
2
27
Male
Married
30000
5
California
4
33 Female
Married
26000
10
Michigan
3
49 Female
Married
15100
25
Virginia
3
26 Female
Married
25000
15
Pennsylvania
4
44
Male
Married
43000
10
Virginia
4
22
Male Never Married/Single 3000
0
California
1
30
Male Never Married/Single 40000
15
New York
4
34 Female
Separated
3000
40
(a) Who are the individuals in this data set?
(b) What variables are measured?
(c) Identify each as categorical or quantitative.
(d) In what units were the quantitative variables measured?
(e) Describe the individual in the first row.
1.1 Analyzing Categorical Data ~ Chapter 1 Pre-Chapter Questions…
Read pages 8 ~ 12
1.
What is the difference between a frequency table and a relative frequency table?
2.
When is it better to use relative frequency tables?
3.
What is the most important thing to remember when making pie charts and bar graphs?
4.
Why do statisticians prefer bar charts?
5.
When is it inappropriate to use a pie chart?
6.
What are some common ways to make a misleading graph?
7.
What is wrong with the following graph?
1.1 Analyzing Categorical Data ~ Chapter 1 Pre-Chapter Questions…
Read pages 12 ~ 18
1.
What is a two-way table?
2.
What is a marginal distribution?
3.
What is a conditional distribution?
3a.
How do we know which variable to condition on?
4.
What is a segmented bar graph?
4a.
Why are they good to use?
5.
What does it mean for two variables to have an association?
5a.
How can you tell by looking at a graph?
6.
Alternate Example: Super Powers
A sample of 200 children from the United Kingdom ages 9–17 was selected from the CensusAtSchool
website. The gender of each student was recorded along with which super power they would most like to
have: invisibility, super strength, telepathy (ability to read minds), ability to fly, or ability to freeze time.
(a) Explain what it would mean if there was no association between gender and superpower preference.
(b) Based on this data, can we conclude there is an association between gender and super power
preference? Justify.
Invisibility
Super Strength
Telepathy
Fly
Freeze Time
Total
Female Male Total
17
13
30
3
17
20
39
5
44
36
18
54
20
32
52
115
85
200
1.2 Displaying Quantitative Data with Graphs ~ Chapter 1 Pre-Chapter Questions…
Read pages 27 ~ 31
1.
When describing the distribution of a quantitative variable, what characteristics should be addressed?
2.
Briefly describe/illustrate the following distribution shapes:
3.
Symmetric
Skewed right
Skewed left
Unimodal
Bimodal
Uniform
Alternate Example: Smart Phone Battery Life
Here is the estimated battery life for each of 9 different smart phones (in minutes).
Make a dotplot of the data and describe what you see.
Smart Phone
Battery Life (minutes)
Apple iPhone
300
Motorola Droid
385
Palm Pre
300
Blackberry Bold
360
Blackberry Storm
330
Motorola Cliq
360
Samsung Moment
330
Blackberry Tour
300
HTC Droid
460
Read pages 31 ~ 34
1.
What is the most important thing to remember when you are asked to compare two distributions?
2.
Alternate Example: Energy Cost: Top vs. Bottom Freezers
How do the annual energy costs (in dollars) compare for refrigerators with top freezers and refrigerators
Dotplot of EnergyCost vs Type
with bottom freezers?
Type
The data below is from the May 2010 issue of Consumer Reports.
bottom
top
56
70
84
98
112
EnergyCost
126
3.
What is the most important thing to remember when making a stemplot?
4.
Alternate Example: Which gender is taller, males or females?
140
A sample of 14-year-olds from the United Kingdom was randomly selected
using the CensusAtSchool website. Here are the heights of the students (in cm).
Make a back-to-back stemplot and compare the distributions.
Male: 154, 157, 187, 163, 167, 159, 169, 162, 176, 177, 151, 175, 174, 165, 165, 183, 180
Female: 160, 169, 152, 167, 164, 163, 160, 163, 169, 157, 158, 153, 161, 165, 165, 159, 168, 153, 166, 158, 158, 166
1.2 Histograms
Read page 35 – 41
The following table presents the average points scored per game (PPG) for the 30 NBA teams in the 2009–2010
regular season. Make a dotplot to display the distribution of points per game. Then, use your dotplot to make a
histogram of the distribution.
Team
PPG
Team
PPG
Team
PPG
Atlanta Hawks
Boston Celtics
101.7
99.2
95.3
97.5
102.1
102
106.5
94
108.8
102.4
Indiana Pacers
Los Angeles Clippers
100.8
95.7
101.7
102.5
96.5
97.7
98.2
92.4
100.2
102.1
Oklahoma City Thunder
Orlando Magic
101.5
102.8
97.7
110.2
98.1
100
101.4
104.1
104.2
96.2
Charlotte Bobcats
Chicago Bulls
Cleveland Cavaliers
Dallas Mavericks
Denver Nuggets
Detroit Pistons
Golden State Warriors
Houston Rockets
Los Angeles Lakers
Memphis Grizzlies
Miami Heat
Milwaukee Bucks
Minnesota Timberwolves
New Jersey Nets
New Orleans Hornets
New York Knicks
Philadelphia 76ers
Phoenix Suns
Portland Trail Blazers
Sacramento Kings
San Antonio Spurs
Toronto Raptors
Utah Jazz
Washington Wizards
How do you make a histogram?
Why would we prefer a relative frequency histogram to a frequency histogram?
What will cause you to lose points on tests and projects (and turn the rest of Mrs. Royal’s hair gray)?
1.3 Describing Quantitative Data with Numbers
Read pages 50 ~ 57
What is the difference between 𝑥̅ and µ ?
What is a resistant measure? Is the mean a resistant measure of center?
How can you estimate the mean of a histogram or dotplot?
Is the median a resistant measure of center? Explain.
How does the shape of a distribution affect the relationship between the mean and the median?
What is the range? Is it a resistant measure of spread? Explain.
What are quartiles? How do you find them?
What is the interquartile range (IQR)?
Is the IQR a resistant measure of spread?
Alternate Example: McDonald’s Beef Sandwiches
Here is data for the amount of fat (in grams) for McDonald’s
beef sandwiches.
Calculate the median and the IQR…
Read page 57 ~ 60
Sandwich
Hamburger
Cheeseburger
Double Cheeseburger
McDouble
Quarter Pounder®
Quarter Pounder® with Cheese
Double Quarter Pounder® with Cheese
Big Mac®
Big N’ Tasty®
Big N’ Tasty® with Cheese
Angus Bacon & Cheese
Angus Deluxe
Angus Mushroom & Swiss
McRib®
Mac Snack Wrap
Fat(g)
9g
12 g
23 g
19 g
19 g
26 g
42 g
29 g
24 g
28 g
39 g
39 g
40 g
26 g
19 g
What is an outlier? How can you identify outliers? Are there outliers in the beef sandwich distribution?
Here is data for the amount of fat (in grams) for
McDonald’s chicken sandwiches.
Are there any outliers in this distribution?
What is the five-number summary?
Sandwich
McChicken ®
Premium Grilled Chicken Classic Sandwich
Premium Crispy Chicken Classic Sandwich
Premium Grilled Chicken Club Sandwich
Premium Crispy Chicken Club Sandwich
Premium Grilled Chicken Ranch BLT Sandwich
Premium Crispy Chicken Ranch BLT Sandwich
Southern Style Crispy Chicken Sandwich
Ranch Snack Wrap® (Crispy)
Ranch Snack Wrap® (Grilled)
Honey Mustard Snack Wrap® (Crispy)
Honey Mustard Snack Wrap® (Grilled)
Chipotle BBQ Snack Wrap® (Crispy)
Chipotle BBQ Snack Wrap® (Grilled)
Draw parallel boxplots for the beef and chicken sandwich data.
Compare these distributions.
Fat(g)
16 g
10 g
20 g
17 g
28 g
12 g
23 g
17 g
17 g
10 g
16 g
9g
15 g
9g
1.3 Standard Deviation
Read page 62–67
In the distribution below, how far are the values from the mean, on average?
1
2
3
4
5
6
7
8
What does the standard deviation measure?
What are some similarities and differences between the range, IQR, and standard deviation?
How is the standard deviation calculated?
What is the variance?
What are some properties of the standard deviation?
Alternate Example: A random sample of 5 students was asked how many minutes they spent doing homework
the previous night. Here are their responses (in minutes): 0, 25, 30, 60, 90.
Calculate and interpret the standard deviation.
What factors should you consider when choosing which summary statistics to use?