1. Chapter 2
Understanding Data

2. The term data is plural. The singular is datum.
Do data have to be numbers?

3. Quantitative vs. Categorical
Weight
Population
Price
Distance in miles
Categorical
Name
Gender
Shirt size (S,M,L,XL)
Student ID number

4. Classify the type of data as quantitative or categorical.
Number of facebook users
Driver’s license number
1st, 2nd, or 3rd place in a race
Time in seconds to run a mile
Social Security Number
Test grade as a percent
Phone number
Percentage of class that passes with an A or a B
Movie rating (G, PG, PG13, R, NC17)
Data such as phone number, SSN, ID number, and driver’s license number are called identifiers.

5. Who? What? When? Where? Why? How?
As we discussed, data must have a context. If possible, answer the 5 W’s (plus an H) when looking at a Statistics problem.
Who?
What?
When?
Where?
Why?
How?

6. Look at the Lance Armstrong example on page 13.
List as many of the W’s as you can for this data set.
Classify each variable as categorical or quantitative; if quantitative, identify the units.

7. Sample vs. Population
A population is an entire group that we want to measure. It includes every element of the set. Example: the population of the Unites States or the population of students in the Union school district.
A sample is a portion of a population. It is a subset. We draw a sample from a population in order to estimate a measure of that population.

8. Today’s assignment: In-Class worksheet on 5 W’s
Ch. 2 Exercises page 17 #13-16, 25
Read Chapter 3