Download Statistics Day 1

Statistics Day 1
Chapter 1: Introduction
Types of data!
• Categorical -- also called count data. Simply
records which category a person or thing falls.
• Quantitative - (numerical) data – numerical values
for which arithmetic operations make sense. You
can find the arithmetic average of this data.
Categorical vs. quantitative variables
Would the variable “monthly rainfall in Michigan” be
considered a categorical or quantitative variable?
a) categorical
b) quantitative
Categorical vs. quantitative variables
(answer)
Would the variable “monthly rainfall in Michigan” be
considered a categorical or quantitative variable?
a) categorical
b) quantitative
Categorical vs. quantitative variables
If we asked people to report their “weight,” would
that variable be considered a categorical or
quantitative variable?
a) categorical
b) quantitative
Categorical vs. quantitative variables
(answer)
If we asked people to report their “weight,” would
that variable be considered a categorical or
quantitative variable?
a) categorical
b) quantitative
Categorical vs. quantitative variables
We then asked people to classify their weight as
underweight, normal, overweight, or obese. Would
this variable now be categorical or quantitative
variable?
a) categorical
b) quantitative
Categorical vs. quantitative variables
(answer)
We then asked people to classify their weight as
underweight, normal, overweight, or obese. Would
this variable now be categorical or quantitative
variable?
a) categorical
b) quantitative
Categorical vs. quantitative variables
What type of data is produced by the answer choices
for this question?
How many times have you
accessed the Internet this
week?
1)
2)
3)
4)
None
Once or twice
Three or four times
More than four times
a) categorical
b) quantitative
Categorical vs. quantitative variables
(answer)
What type of data is produced by the answer choices
for this question?
How many times have you
accessed the Internet this
week?
1)
2)
3)
4)
a) categorical
b) quantitative
None
Once or twice
Three or four times
More than four times
Example Question 1
State
Number of
family
Members
Age
Gender
Marital Status
Total
Income
Travel
time
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
30000
40
Distribution
• The distribution of a variable tells us what values the
variable takes and how often it takes these
variables.
Example 2
• Example 2: Jake is a car buff who wants to find out
more about the vehicles that students at his school drive.
He gets permission to go to the student parking lot and
record some data. Late he does some research about
each model of car on the internet. Finally, Jakes makes
a spread sheet that includes each car’s model, year,
color, number of cylinders, gas mileage, weight, and
whether it has a navigation system.
• Who are the individuals in Jake’s study?
•
• What variables did Jake measure? Identify each as
categorical or quantitative.
Statistical Inferences
• uses collected data to make generalizations about
the entire group. Produces answers to specific
questions and a statement of how confident we
can be that the answer is correct.
• (NOTE: We cannot predict with absolute certainty!
We cannot make predictions about individual
cases!)
Activity 1
• Hiring Discrimination
Assignment
• Page 7 1,2,3,7,8