Time to Practice – Week Four

CompleteParts A, B, and C below.

Some questions in Part A require that you access data fromStatistics for People Who (ThinkThey) Hate Statistics.This data is available on the student website under the Student Text Resources link.

1. Using the data in the file named Ch. 11 Data Set 2, test the research hypothesis at the .05 level of significance that boys raise their hands in class more often than girls. Do this practice problem by hand using a calculator. What is your conclusion regarding the research hypothesis? Remember to first decide whether this is a one- or two-tailed test.

2. Using the same data set (Ch. 11 Data Set 2), test the research hypothesis at the .01 level of significance that there is a difference between boys and girls in the number of times they raise their hands in class. Do this practice problem by hand using a calculator. What is your conclusion regarding the research hypothesis? You used the same data for this problem as for Question 1, but you have a different hypothesis (one is directional and the other is nondirectional). How do the results differ and why?

3. Practice the following problems by hand just to see if you can get the numbers right. Using the following information, calculate thettest statistic.

a.

b.

c.

4. Using the results you got from Question 3 and a level of significance at .05, what are the two-tailed critical values associated with each? Would the null hypothesis be rejected?

5. Using the data in the file named Ch. 11 Data Set 3, test the null hypothesis that urban and rural residents both have the same attitude toward gun control. Use IBM^®SPSS^®software to complete the analysis for this problem.

6. A public health researcher tested the hypothesis that providing new car buyers with child safety seats will also act as an incentive for parents to take other measures to protect their children (such as driving more safely, child-proofing the home, and so on). Dr. L counted all the occurrences of safe behaviors in the cars and homes of the parents who accepted the seats versus those who did not. The findings: a significant difference at the .013 level. Another researcher did exactly the same study; everything was the same—same type of sample, same outcome measures, same car seats, and so on. Dr. R’s results were marginally significant (recall Ch. 9) at the .051 level. Which result do you trust more and why?

7. In the following examples, indicate whether you would perform attest of independent means or dependent means.

a. Two groups were exposed to different treatment levels for ankle sprains. Which treatment was most effective?

b. A researcher in nursing wanted to know if the recovery of patients was quicker when some received additional in-home care whereas when others received the standard amount.

c. A group of adolescent boys was offered interpersonal skills counseling and then tested in September and May to see if there was any impact on family harmony.

d. One group of adult men was given instructions in reducing their high blood pressure whereas another was not given any instructions.

e. One group of men was provided access to an exercise program and tested two times over a 6-month period for heart health.

8. For Ch. 12 Data Set 3, compute thetvalue and write a conclusion on whether there is a difference in satisfaction level in a group of families’ use of service centers following a social service intervention on a scale from 1 to 15. Do this exercise using IBM^®SPSS^®software, and report the exact probability of the outcome.

9. Do this exercise by hand. A famous brand-name manufacturer wants to know whether people prefer Nibbles or Wribbles. They sample each type of cracker and indicate their like or dislike on a scale from 1 to 10. Which do they like the most?

Nibbles rating	Wribbles rating
9	4
3	7
1	6
6	8
5	7
7	7
8	8
3	6
10	7
3	8
5	9
2	8
9	7
6	3
2	6
5	7
8	6
1	5
6	5
3	6

10. Using the following table, provide three examples of a simple one-way ANOVA, two examples of a two-factor ANOVA, and one example of a three-factor ANOVA. Complete the table for the missing examples. Identify the grouping and the test variable.

Design	Grouping variable(s)	Test variable
Simple ANOVA	Four levels of hours of training—2, 4, 6, and 8 hours	Typing accuracy
	Enter Your Example Here	Enter Your Example Here
	Enter Your Example Here	Enter Your Example Here
	Enter Your Example Here	Enter Your Example Here
Two-factor ANOVA	Two levels of training and gender (two-way design)	Typing accuracy
	Enter Your Example Here	Enter Your Example Here
	Enter Your Example Here	Enter Your Example Here
Three-factor ANOVA	Two levels of training, two of gender, and three of income	Voting attitudes
	Enter Your Example Here	Enter Your Example Here

11. Using the data in Ch. 13 Data Set 2 and the IBM^®SPSS^®software, compute theFratio for a comparison between the three levels representing the average amount of time that swimmers practice weekly (< 15, 15–25, and > 25 hours) with the outcome variable being their time for the 100-yard freestyle. Does practice time make a difference? Use the Options feature to obtain the means for the groups.

12. When would you use a factorial ANOVA rather than a simple ANOVA to test the significance of the difference between the averages of two or more groups?

13. Create a drawing or plan for a 2 × 3 experimental design that would lend itself to a factorial ANOVA. Identify the independent and dependent variables.

14. John is interested in determining if a new teaching method, the involvement technique, is effective in teaching algebra to first graders. John randomly samples six first graders from all first graders within the Lawrence City School System and individually teaches them algebra with the new method. Next, the pupils complete an eight-item algebra test. Each item describes a problem and presents four possible answers to the problem. The scores on each item are 1 or 0, where 1 indicates a correct response and 0 indicates a wrong response. The IBM^®SPSS^®data file contains six cases, each with eight item scores for the algebra test.

Conduct a one-samplettest on the total scores. On the output, identify the following:

a. Mean algebra score

b.Ttest value

c.Pvalue

15. Marvin is interested in whether blonds, brunets, and redheads differ with respect to their extrovertedness. He randomly samples 18 men from his local college campus: six blonds, six brunets, and six redheads. He then administers a measure of social extroversion to each individual.

Conduct a one-way ANOVA to investigate the relationship between hair color and social extroversion. Conduct appropriate post hoc tests. On the output, identify the following:

a.Fratio for the group effect

b. Sums of squares for the hair color effect

c. Mean for redheads

d.Pvalue for the hair color effect

Completethe questions below. Be specific and provide examples when relevant.

Citeany sources consistent with APA guidelines.

Question	Answer
What is meant by independent samples? Provide a research example of two independent samples.
When is it appropriate to use attest for dependent samples? What is the key piece of information you must know in order to decide?
When is it appropriate to use an ANOVA? What is the key piece of information you must know in order to decide?
Why would you want to do an ANOVA when you have more than two groups, rather than just comparing each pair of means with attest?

University of Phoenix Material

Time to Practice – Week Five

Complete Parts A, B, and C below.

Some questions in Part A require that you access data fromStatistics for People Who (Think They) Hate Statistics.This data is available on the student website under the Student Text Resources link.

1. Use the following data to answer Questions 1a and 1b.

Total no. of problems correct (out of a possible 20)	Attitude toward test taking (out of a possible 100)
17	94
13	73
12	59
15	80
16	93
14	85
16	66
16	79
18	77
19	91

a. Compute the Pearson product-moment correlation coefficient by hand and show all your work.

b. Construct a scatterplot for these 10 values by hand. Based on the scatterplot, would you predict the correlation to be direct or indirect? Why?

2. Rank the following correlation coefficients on strength of their relationship (list the weakest first):

+.71

+.36

–.45

.47

–.62

3. Use IBM^® SPSS^® software to determine the correlation between hours of studying and grade point average for these honor students. Why is the correlation so low?

Hours of studying	GPA
23	3.95
12	3.90
15	4.00
14	3.76
16	3.97
21	3.89
14	3.66
11	3.91
18	3.80
9	3.89

4. Look at the following table. What type of correlation coefficient would you use to examine the relationship between ethnicity (defined as different categories) and political affiliation? How about club membership (yes or no) and high school GPA? Explain why you selected the answers you did.

Level of Measurement and Examples
Variable X	Variable Y	Type of correlation	Correlation being computed
Nominal (voting preference, such as Republican or Democrat)	Nominal (gender, such as male or female)	Phi coefficient	The correlation between voting preference and gender
Nominal (social class, such as high, medium, or low)	Ordinal (rank in high school graduating class)	Rank biserial coefficient	The correlation between social class and rank in high school
Nominal (family configuration, such as intact or single parent)	Interval (grade point average)	Point biserial	The correlation between family configuration and grade point average
Ordinal (height converted to rank)	Ordinal (weight converted to rank)	Spearman rank correlation coefficient	The correlation between height and weight
Interval (number of problems solved)	Interval (age in years)	Pearson product-moment correlation coefficient	The correlation between number of problems solved and the age in years

5. When two variables are correlated (such as strength and running speed), it also means that they are associated with one another. But if they are associated with one another, then why does one not cause the other?

6. Given the following information, use Table B.4 in Appendix B ofStatistics for People Who (Think They) Hate Statistics to determine whether the correlations are significant and how you would interpret the results.

a. The correlation between speed and strength for 20 women is .567. Test these results at the .01 level using a one-tailed test.

b. The correlation between the number correct on a math test and the time it takes to complete the test is –.45. Test whether this correlation is significant for 80 children at the .05 level of significance. Choose either a one- or a two-tailed test and justify your choice.

c. The correlation between number of friends and grade point average (GPA) for 50 adolescents is .37. Is this significant at the .05 level for a two-tailed test?

7. Use the data in Ch. 15 Data Set 3 to answer the questions below. Do this one manually or use IBM^®SPSS^® software.

a. Compute the correlation between income and level of education.

b. Test for the significance of the correlation.

c. What argument can you make to support the conclusion that lower levels of education cause low income?

8. Use the following data set to answer the questions. Do this one manually.

a. Compute the correlation between age in months and number of words known.

b. Test for the significance of the correlation at the .05 level of significance.

c. Recall what you learned in Ch. 5 ofSalkind (2011)about correlation coefficients and interpret this correlation.

Age in months	Number of words known
12	6
15	8
9	4
7	5
18	14
24	18
15	7
16	6
21	12
15	17

9. How does linear regression differ from analysis of variance?

10. Betsy is interested in predicting how many 75-year-olds will develop Alzheimer’s disease and is using level of education and general physical health graded on a scale from 1 to 10 as predictors. But she is interested in using other predictor variables as well. Answer the following questions.

a. What criteria should she use in the selection of other predictors? Why?

b. Name two other predictors that you think might be related to the development of Alzheimer’s disease.

c. With the four predictor variables (level of education, general physical health, and the two new ones that you name), draw out what the model of the regression equation would look like.

11. Joe Coach was curious to know if the average number of games won in a year predicts Super Bowl performance (win or lose). The x variable was the average number of games won during the past 10 seasons. The y variable was whether the team ever won the Super Bowl during the past 10 seasons. Refer to the following data set:

Team	Average no. of wins over 10 years	Bowl? (1 = yes and 0 = no)
Savannah Sharks	12	1
Pittsburgh Pelicans	11	0
Williamstown Warriors	15	0
Bennington Bruisers	12	1
Atlanta Angels	13	1
Trenton Terrors	16	0
Virginia Vipers	15	1
Charleston Crooners	9	0
Harrisburg Heathens	8	0
Eaton Energizers	12	1

a. How would you assess the usefulness of the average number of wins as a predictor of whether a team ever won a Super Bowl?

b. What’s the advantage of being able to use a categorical variable (such as 1 or 0) as a dependent variable?

c. What other variables might you use to predict the dependent variable, and why would you choose them?

From Salkind (2011). Copyright © 2012 SAGE. All Rights Reserved. Adapted with permission.

Some questions in Part B require that you access data fromUsing SPSS for Windows and Macintosh. This data is available on the student website under the Student Text Resources link. The data for this exercise is in the data file named Lesson 33 Exercise File 1.

Peter was interested in determining if children who hit a bobo doll more frequently would display more or less aggressive behavior on the playground. He was given permission to observe 10 boys in a nursery school classroom. Each boy was encouraged to hit a bobo doll for 5 minutes. The number of times each boy struck the bobo doll was recorded (bobo). Next, Peter observed the boys on the playground for an hour and recorded the number of times each boy struck a classmate (peer).

1. Conduct a linear regression to predict the number of times a boy would strike a classmate from the number of times the boy hit a bobo doll. From the output, identify the following:

a. Slope associated with the predictor

b. Additive constant for the regression equation

c. Mean number of times they struck a classmate

d. Correlation between the number of times they hit the bobo doll and the number of times they struck a classmate

e. Standard error of estimate

From Green & Salkind (2011). Copyright © 2012 Pearson Education. All Rights Reserved. Adapted with permission.

Complete the questions below. Be specific and provide examples when relevant.

Cite any sources consistent with APA guidelines.

Question	Answer
Draw a scatterplot of each of the following: · A strong positive correlation · A strong negative correlation · A weak positive correlation · A weak negative correlation Give a realistic example of each.
What is the coefficient of determination? What is the coefficient of alienation? Why is it important to know the amount of shared variance when interpreting both the significance and the meaningfulness of a correlation coefficient?
If a researcher wanted to predict how well a student might do in college, what variables do you think he or she might examine? What statistical procedure would he or she use?
What is the meaning of the p value of a correlation coefficient?