Complete the even-numbered problems for the designated chapter(s) in the textbook. Students are highly encouraged to complete all problems in each chapter, as odd-numbered problems increase understanding of even-numbered problems (answers to odd numbered problems are located in appendix A at the back of the text.

1. Chapter 6, module 12, exercises 2 and 4

(2). You read in a health magazine about a study in which a new therapy technique for depression was examined. A group of depressed individuals volunteered to participate in the study, which lasted 9 months. There were 50 participants at the beginning of the study and 29 at the end of the 9 months. The researchers claimed that of those who completed the program, 85% improved. What possible confounds can you identify in this study?

(4). What are internal validity and external validity? Why are they so important to researchers?

Complete the even-numbered problems for the designated chapter(s) in the textbook. Students are highly encouraged to complete all problems in each chapter, as odd-numbered problems increase understanding of even-numbered problems (answers to odd numbered problems are located in appendix A at the back of the text.

1. Chapter 7, module 15, exercises 4 and 6

(4). Calculate the mean, median, and mode for the data set in Exercise 1. Is the distribution normal or skewed? Which measure of central tendency is most appropriate for this distribution? Why?

(Exercise 1) The following data represent a distribution of speeds (in miles per hour) at which individuals were traveling on a highway.

64 80 64 70

76 79 67 72

65 73 68 65

67 65 70 62

67 68 65 64

Organize these data into a frequency distribution with frequency (*f*) and relative frequency (*rf*) columns.

(6). Calculate the range and standard deviation for the following five distributions:

a. 1, 2, 3, 4, 5, 6, 7, 8, 9 b. 4, 3, 2, 1, 0, 1, 2, 3, 4 c. 10, 20, 30, 40, 50, 60, 70, 80, 90 d. 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 e. 100, 200, 300, 400, 500, 600, 700, 800, 900

Complete the even-numbered problems for the designated chapter(s) in the textbook. Students are highly encouraged to complete all problems in each chapter, as odd-numbered problems increase understanding of even-numbered problems (answers to odd numbered problems are located in appendix A at the back of the text.

1. Chapter 8, module 17, exercises 2 and 4

(2). To test the hypothesis in Exercise 1, the admissions counselors select a random sample of freshmen and compare their scores on the SAT to those of the population of upperclassmen. They find that the freshmen do in fact have a higher mean SAT score. However, what they are

unaware of is that the sample of freshmen was not representative of all freshmen at Brainy University. In fact, the sample overrepresented those with high scores and underrepresented those with low scores. What type of error (Type I or Type II) did the counselors make?

4. What are the appropriate *H*0 and *H*a for each of the following research studies? In addition, note whether the hypothesis test is one- or two-tailed.

a. A study in which researchers want to test

whether there is a difference in spatial

ability between left- and right-handed

people

b. A study in which researchers want to test

whether nurses who work 8-hour shifts

deliver higher-quality work than those

who work 12-hour shifts

c. A study in which researchers want to

determine whether crate-training puppies

is superior to training without a crate

2. Chapter 8, module 18, exercises 2 and 4

(2). What is the standard error of the difference between means?

A college student is interested in whether there is a difference between male and female students in the amount of time spent studying each week. The student gathers information from a random sample of male and female students on campus. Amount of time spent studying is normally distributed. The data follow.

*Males Females*

27 25

25 29

19 18

10 23

16 20

22 15

14 19

a. What statistical test should be used to analyze these data? b. Identify *H*0 and *H*a for this study. c. Conduct the appropriate analysis.

d. Should *H*0 be rejected? What should the researcher conclude?

e. If significant, compute the effect size and interpret.

f. If significant, draw a graph representing the data.

1. Chapter 9, module 19, exercise 2, 4, and 6

(2). What are the assumptions of a correlated group’s *t *test?

(4). What measure of effect size is used for a correlated-groups *t *test?

(6). The student in Question 5 from Module 18 decides to conduct the same study using a within-participants design in order to control for differences in cognitive ability. He selects a random sample of participants and has them study different material of equal difficulty in both the music and no music conditions. The data appear below. As before, they are measured on an intervalratio scale and are normally distributed.

*Music No Music*

6 10

7 7

6 8

5 7

6 7

8 9

8 8

a. What statistical test should be used to analyze these data?

b. Identify *H*0 and *H*a for this study.

c. Conduct the appropriate analysis.

d. Should *H*0 be rejected? What should the researcher conclude?

e. If significant, compute the effect size and interpret.

f. If significant, draw a graph representing the data.

Subject | Mathematics |

Due By (Pacific Time) | 09/05/2014 12:00 am |

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