Homework #3

Due:  Sept 30th, Tuesday
Topic: Chapter 3, 4
 

Chapter 3 Exercises:
Page 137 

#3.2 

Page 149

#3.18

Page 157 - 159

#3.22

Page 167 - 181

#3.32, #3.34, #3.54 

Additional problem #1

In a study to investigate the effects of smoking on blood pressure, it was found that smokers in general had higher blood pressure compared to non-smokers. A total of 1050 adults, comprising of 550 males and 500 females were considered for the study.

a.What is the response variable?
b.What is the explanatory variable?

c.A criticism of the study was that most smokers were males and it is known that males generally have higher blood pressure compared to females. Thus in this study, gender is a: (select one)

(i) response variable; 
(ii) continuous variable; 
(ii) confounding variable; 
(iv) control variable

d.The investigators of the study stated that they adjusted for the criticism in part (c) but there was still evidence that smoking was (positively) associated to blood pressure. Suppose the hypotheses being tested are as follows:
H0: There is no association between smoking and blood pressure.
H1: There is an association between smoking and blood pressure.
The evidence implied that the results were statistically significant at 5%. Answer each question.

(i)The results are also statistically significant at 2.5% Yes No Can?t tell

(ii)The results are also statistically significant at 10% Yes No Can?t tell
(iii)The null hypothesis was rejected. Yes No Can't tell
(iv)The p-value was less than or equal to 5% Yes No Can't tell

Additional problem #2

In order to assess the effect of amount of exercise on cholesterol level, a researcher sampled 100 people from a local gym who exercises regularly and 100 people from the surrounding community who did not exercise regularly. Each of the 200 subjects reported to a clinic to have their cholesterol measured. The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol level was not aware whether subjects exercised regularly or not.

a.This is: (select one)
(i)an observational study;
(ii)an experiment but not a double-blind experiment;
(iii)a double-blinded experiment;

b.Give the response variable and the explanatory variable.

Chapter 4 problems

#4.8 Page 197

#4.18 Page 212

#4.58 Page 249