Chapter 10 Module 22: Tests for Ordinal Data 8.A researcher wants to compare the maturity level of students who volunteer for community service to the maturity level of those who do not. She believes that completing community service leads to higher maturity scores. Maturity scores tend to be skewed (not normally distributed). The maturity scores follow. Higher scores indicate high

Chapter 9 Module 18:  Correlational Research

1. Label each of the scatterplots below to indicate whether the correlation it shows is
   positive, negative, curvilinear, or zero or near zero.

 

1.  ________________________          b.  ________________________
2.  ________________________          d.  ________________________

 

 

2. In a recent study the correlation between self-esteem and depression was found to be –0.64.
   Tom interprets this to mean that low levels of self-esteem lead to high levels of depression.
3. Explain what a correlation of –0.64 means.

 

 

 

 

1. Calculate the coefficient of determination for this correlation and explain what this indicates. SHOW YOUR CALCULATIONS.

 

 

 

1. What is incorrect about Tom’s interpretation of the correlation?

 

 

 

Chapter 9 Module 19: Correlation Coefficients

3. Use the following data to answer the questions below. (This is based on Module 19 Exercise 4.)

 

	Student	IQ Score	Statistics Exam Score	IQ z Score	Stat Exam z Score	ZIQZStat
	1	140	47	2.367	1.163	2.754
	2	98	32	-1.413	-1.745	2.466
	3	105	38	-0.783	-0.582	0.456
	4	120	40	0.567	-0.194	-0.110
	5	119	40	0.477	-0.194	-0.093
	6	114	43	0.027	0.388	0.010
	7	102	33	-1.053	-1.551	1.634
	8	112	47	-0.153	1.163	-0.178
	9	111	46	-0.243	0.969	-0.236
	10	116	44
Means		113.70	41.00	r=
Dev Squared		1,234.10	266.00	r2=
Sample Std Dev		11.11	5.16

 

 

10. Fill in the last three columns for Student 10. In other words, determine the z scores for Student 10 and then the cross-product that goes in the last column. SHOW YOUR CALCULATIONS.

 

 

 

 

 

1. Determine the Pearson product-moment correlation between IQ scores and statistics exam scores. SHOW YOUR CALCULATIONS.

 

 

 

 

 

 

 

1. Calculate the coefficient of determination for the correlation coefficient between IQ scores and statistics exam scores. Explain what this means.

 

 

 

 

 

Chapter 09 Module 20:  Regression Analysis

4. For the data in Question 3 above, determine the regression equation for IQ scores and statistics exam scores. Let Y’ represent the predicted statistics exam score for a certain IQ score X.

 

 

 

 

 

 

 

 

5. Assume that the regression equation for statistics exam scores and psychology exam scores is
   Y’ = 0.586X + 17.43, where Y’ represents the predicted statistics exam score and X is a particular psychology exam score. What would you expect the statistics exam score to be for each of the following individuals whose psychology exam scores are given?

 

Student	Psychology Exam Score	Statistics Exam Score
Linda	30
Marilyn	39
Heidi	48

 

Chapter 10 Module 21:  Chi-Square Tests

6. According to the U.S. Bureau of the Census, 75% of adults regularly drank alcohol in 1985. An investigator predicts that fewer adults drink now than they did back then. A sample of 100 adults is asked about their current drinking habits and 67 report drinking while 33 report not drinking. Fill in the table below as though you were going to conduct a c2 goodness-of-fit test.

 

Frequencies	Report Drinking	Report Not Drinking	Totals
Observed
Expected
Totals

 

 

7. In your introductory psychology class, more men seem to sit near the door and more women seem to sit away from the door. To determine whether men sit near the door significantly more often than women, you collect data on the seating preferences for the students in your class. The data appear below, and the questions follow.

 

	Males	Females
Near the Door	25	14
Away from the Door	12	20

 

1. Identify H₀and H_a for this study.

 

 

 

 

 

 

1. Conduct a c²test of independence. SHOW YOUR CALCULATIONS.

 

 

 

 

 

1. Should H₀be rejected? What should the researcher conclude?

 

 

 

Chapter 10 Module 22:  Tests for Ordinal Data

8. A researcher wants to compare the maturity level of students who volunteer for community service to the maturity level of those who do not. She believes that completing community service leads to higher maturity scores. Maturity scores tend to be skewed (not normally distributed). The maturity scores follow. Higher scores indicate higher maturity levels. (This is Module 22 Exercise 4.)

 

	Sorted Data	Original Data	Original Data	Sorted Data
Community Service Rank	Community Service	Community Service	No Community Service	No Community Service	No Community Service Rank
	41	41	33	13
	48	48	41	22
	55	61	54	26
	61	72	13	33
	72	83	22	41
	83	55	26	54
Sum =					Sum =

 

1. Fill in the ranks in the first and last columns, giving the lowest number a rank of 1, etc. Then write the sum of the ranks in the first column at the bottom of that column and the sum of the ranks in the second column at the bottom of that column.

 

1. For n₁=6 and n₂=6, Table A.8 gives 28 as the critical value. Which sum is compared to this critical value to determine if there is a significant difference between those who complete community service and those who do not?

 

 

1. Is there a significant difference or not? What do you conclude about community service?