1. Collect and Interpret Data
Notes 1-1
Collect and Interpret Data

2. Data –
Gathered information
Sample –
a part of the group being surveyed.

3. Types of Sampling Random Sampling –
each member of the population has an equal chance of being selected
Members are chosen independently of one another.
Example: Put 100 names into a hat, then drawing 20 of the names.

4. Convenience Sampling –
the sample is chosen only because it is easily available.
Example: polling ten students who happen to be sitting near you in the cafeteria.

5. Systematic Sampling –
After a population is ordered in some way, the sample is chosen according to a pattern.
Example: select every 10th item from a long list

6. Cluster Sampling –
members of the population are chosen at random from a particular part of the population and then polled in clusters.
Example: choose a random city and go to the police stations in that city and ask the officers which type of donut they like best.

7. Which reflects the random sampling method that a health club owner might use to identify the most popular exercise machine in the club?
A. Ask the first 20 members who enter the club one morning.
B. Ask the members whose phone numbers end with the digit 7.
C. Ask members who live on the six busiest streets in town.
Choice B. Since phone numbers are assigned at random, those members whose phone numbers end in 7 represent a random sample.

8. In an assembly line, every twentieth rowing machine out of 500 is quality tested. Two are defective.   A. What kind of sampling does this situation represent?   B. What might be an advantage of this kind of sampling?          
a. This example represents systematic sampling.
b. An advantage is that the sample comes from the whole population.

9. Which automobile has faster acceleration?
Car A (seconds)
Car B (seconds)
Zero to 30 mi/h
1.8
3.2
Zero to 40 mi/h
2.8
4.7
Zero to 50 mi/h
3.9
6.4
Zero to 60 mi/h
5.1
8.8
Zero to 70 mi/h
6.8
11.6
Zero to 80 m/h
8.6
15.0
Car A accelerates from zero to each measured speed in fewer seconds than Car B. Car A has better acceleration.

10. Homework:
Page , 17-30, 32-34