1. Other types of samples…
5.3: SAMPLING
Other types of samples…

2. Review:
Three sample designs covered so far:
Simple Random Sample (SRS)
Voluntary Response Sample
Convenience Sample

3. Other ways to take samples
Example:
At a university, there are 1500 professors. However, 1000 are male and 500 are female. To take an accurate sample of the university faculty’s opinions, we decide to take a sample of 100 male professors and 50 female. Their total sample is these 150 professors.
Why is this not an SRS? What was their process? Why is this sampling method better than just an SRS?

4. Stratified Random Sample: (NOT simple random sample)
Divide population into groups with something in common (called STRATA)
Example: gender, age, etc.
2) Take separate SRS in each strata and combine these to make the full sample
- can sometimes be a % of each strata

5. Try p. 246 #62 BASKETBALL Instructions: Assign 01-19 to each player
Use a TRD and read off 2 digits at a time
Ignore 00,20-99, and repeats
Read off 7 numbers
01 Arenas
06 Duncan
11 Leslie
16 Robinson
02 Billups
07 Farmar
12 McGrady
17 Stoudamire
03 Brand
08 Fowles
13 Miller
18 Taurasi
04 Bryant
09 Gasol
14 Nowitzki
19 Wade
05 Carter
10 Iverson
15 Parker
Line 101:

6. Try p. 246 #62 GOLF (Use line 103) Instructions:
Use a TRD and read off 1 digit at a time
Assign 1-9 to each player and ignore 0
Read off 3 numbers and ignore repeats
1 Cramer
4 Kim
7 Singh
2 Els
5 Mickelson
8 Wie
3 Gulbis
6 Prammanasudh
9 Woods
Line 103:

7. Try p #68 (a)
First separate the faculty into the 2000 males and 500 females
MALES
Use TRD and read off 4 digits at a time
Assign the males #0001 – 2000, and ignore 0000,
Read off 200 numbers and ignore repeats
Females
Use TRD and read off 3 digits at a time
Assign the females #001 – 500, and ignore 000,
The total 400 faculty selected are our sample

8. Systematic Sample:
* Randomly picking a first individual, and then selecting every ____ person after that.
* Example: Interview every 5th person that walks thru the back door of CB South in the morning.
* Example: Write down the type of car in every 3rd spot in the CB South parking lot.

9. Cluster Sample
Pick a certain area/part of the population.
Try to get every individual in that selection
Example: select one lunch period, and talk to everyone at that lunch
Census
Sample everyone in the entire population.

10. EXAMPLE: We need to survey a random sample of 30 passengers on a flight from San Francisco to Tokyo. Name each sampling method described below:
Pick every 10th passenger that boards
From the boarding list, randomly choose 5 people flying first class, and 25 of the other passengers
Randomly generate 30 seat numbers and survey the passengers who sit there
Randomly select a seat position (right window, left window, right aisle, etc.) and survey all people in those seats

11. Random Rectangles Activity!