1. Homework: pg. 349 #21, 24, 27-31
21.) A. The individuals are adults, presumably those who are eligible to vote, in the country.
B. The individuals are employed women who are members of the local business and professional women’s club.
The individuals are households in the United States.

2. 24. ) In order to increase the accuracy of its poll results
24.) In order to increase the accuracy of its poll results. Larger samples give less variable results than smaller samples. 27.) It is not an SRS because some samples of size 250 have no chance of being selected. 28.) A. The question is clear and is slanted more elicit more responses against gun control. B. The phrasing of this question will tend to make people respond in favor of a nuclear freeze.

3. 29.) A sample from a smaller subgroup gives less information about the population. “Men” constituted only about one-third of our sample, so we know less about that group than we know about all adults. 30.) The chance of being interviewed is 3/30 for students over 21 and 2/20 for student under age 21. It is not an SRS because not all combinations of students have an equal chance of being interviewed. 31.) One possibility: obtain a list of schools, stratified by size or location (rural, suburban, and urban). Choose SRSs of schools from each stratum. Then choose SRSs of students from the selected schools.

4. 5.2 Designing Experiments

5. Experiments units—individuals in an experiment subjects—humans
factors—explanatory variable(s)—can be more than one
treatment—specific experimental condition (list out every possibility)
response—what you are measuring

6. Experiments placebo—dummy treatment
control group—group who receives no treatment or placebo treatment
Double blind experiment —neither subjects nor those who measure the response variable know which treatment a subject received
Helps treat every subject the same, regardless of treatment

7. Pg 357 #33 Units: Pine seedlings Factors: Amount of sunlight
The ability to grow in shade may help pines found in the dry forests of Arizona to resist drought. How well do these pines grow in the shade? Investigators planted pine seedlings in a greenhouse in either full light, light reduced to 25% of normal by shade cloth, or light reduced to 5% of normal. At the end of the study, they dried the trees and weighed them.
Units:
Pine seedlings
Factors:
Amount of sunlight
Treatments:
Full light; 25% light; 5% light
Response:
Weight of trees

8. Pg 355 Ex 5.14 Units/Subjects: Undergraduates Factors:
What are the effects of repeated exposure to an advertising message? The answer may depend both on the length of the ad and on how often it is repeated. They used undergraduate students. All students viewed a 40 minute TV program that included ads for a digital camera. Some students saw a 30 second or 90 second commercial. The same commercial 1, 3, or 5 times. After viewing, students were asked their views about the camera.
Units/Subjects:
Undergraduates
Factors:
Length & # of times
Treatments:
All 6 possibilities
Response:
View of camera

9. HW: pg 357 #34-36, 38