CONTENTS
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Chapter 8: Introduction to Hypothesis Testing .............ccccsscsssccssssccsssseees 180 Chapter 9: Introduction to the t Statistic .............:ccccsssscsssssssesssssssscsesseees 184
Chapter 10: The t Test for Two Independent Samples ..............c.sscssssssssese 187 Chapter 11: The t Test for Two Related Samples ..............csssccsccsssssssseseees 191
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Chapter 15: Correlation and Regression ............cccscccssssscssssssssesscessscosceees 210 Chapter 16: Hypothesis Tests with Chi-Square ............ccccsccsssscsssessessssees 215
Section I Test Bank
The first section of this Instructor’s Manual consists of a test bank of exam items to accompany the Statistics textbook. There are approximately 25 multiplechoice questions, 25 true/false questions, and a handful of other text questions for each of the 19 chapters in the book. Answers are provided for all of the test items, and the multiple-choice and true/false questions are cross-referenced to specific pages in the textbook. Finally, you should note that some of the exam items are marked with a www to indicate that these items are available to students on the Study Center web site at www.wadsworth.com.
Section I: Test Bank - page |!
Chapter | Introduction to Statistics Multiple-Choice Questions
Answer a page 3 www
1. A researcher is interested in the eating behavior of rats and selects a group of 25 rats to be tested in a research study. The group of 25 rats isa a. sample b. statistic c. population d. parameter
Answer b page 4 www
2. A researcher is interested in the effect of St. Johns Wort on memory. A group of 25 college students is selected to participate in a research study. The average memory score obtained for the students is a a. sample b. statistic c. population d. parameter
Answer ¢ page 3
3. A researcher is curious about the average IQ of registered voters in the state of Florida. The entire group of registered voters in Florida is an example of a a. sample b. statistic c. population d. parameter
Answer d
4. A researcher is curious about the average IQ of registered voters in the state of
page 4
Florida.
If this average could be obtained, it would be an example of a
a. sample b. statistic c. population d. parameter
Chapter 1: Exam Items - page 2
Answer c
page 3
5. Although research questions typically concern a typically examines a a. sample, population
, aresearch study
b. statistic, sample
c. population, sample d. parameter, population Answer a page 4
6. The relation between a statistic and a parameter is the same as the relation between a. a sample and a population b. a dependent variable and an independent variable c. descriptive statistics and inferential statistics d. an operational definition and a hypothetical construct
Answer d
7. Statistical methods that use sample data to answer general questions about a population are called a. parameters b. statistics ¢c. descriptive statistics d. inferential statistics
page 5
Answer c
page 5 WWWw
Answer a
page 4
8. Statistical techniques that summarize, organize, and simplify data are classified as . population statistics . sample statistics . descriptive statistics . inferential statistics aaa 9. A characteristic, usually a numerical value, that describes an entire population of scores is a a. parameter b. statistic c. variable d. constant
Answer b page 4
10. A characteristic, usually a numerical value, that describes a sample of scores is a parameter
statistic variable . constant aoe
Chapter 1: Exam Items - page 3
Answer b page 15
11.
Using letter grades (A, B, C, D, and F) to classify student performance on an
exam is an example of measurement on a(n)
scale of measurement.
a. nominal b. ordinal c. interval d. ratio Answer d
page 15
12.
Determining a person's age (in years) would involve measurement on a(n) scale of measurement. nominal . ordinal . interval a=6. Tatio
13. Determining a person's occupation would involve measurement on a(n) scale of measurement. a. nominal b. ordinal c. interval d. ratio Answer d
page 16
Answer c
page 11
14. After measuring a set of individuals, a researcher finds that Bob's score is three times greater than Jane's score. These measurements must come from a(n) scale. . nominal . ordinal . interval oo (oF man) . ratio 15. In an experiment, the researcher manipulates the or measures the variable.
variable and observes
a. population, sample b. sample, population c. independent, dependent d. dependent, independent 16. A researcher observed that preschool children who were placed in a red room for their play period showed more aggression than children who were placed in a blue room. For this study, what is the independent variable? a. preschool children b. color of the room c. amount of aggression d. the children's play
Chapter 1: Exam Items - page 4
17. Ina study evaluating the effectiveness of a new medication designed to reduce cholesterol, one sample of individuals is given the medicine and a second sample is given an inactive placebo. Cholesterol level is measured for each individual. For this study, what is the dependent variable? the medication . the placebo cholesterol level . the individuals given the medication paon Answer d page 17
18. Which of the following is not a continuous variable? a. time to solve a problem b. temperature c. height d. number of children in a family
Answer d page 17
19. A variable that has an infinite number of possible values between any two specific measurements is called a(n) variable. a. independent b. dependent c. d.
Answer c
page 17 WWW
discrete continuous
20. A variable that consists of indivisible categories with no other scores existing between neighboring categories is called a(n) variable. a. independent b. dependent c. discrete d. continuous
Answer C
21. What is the first step to be performed in the following mathematical
page 21
expression?
L(X +2)
a. square each value b. sum the squared values c. add 2 points to each value d. square the sum of the values
22. What is the final step to be performed in the following mathematical expression? L(X +2) a. square each value b. sum the squared values c. add 2 points to each value d. square the sum of the values
Chapter 1: Exam Items - page 5
Answer b
page 21
Answer a
page 23
23. For the following scores, what is ©X*? a. 16 b. 24 c. 64 d. (24) = 576
Scores: 2, 0, 4, 2
24. For the following scores, what is (ZX)*? a. 16 b. 24 c. 64 d. (24) = 576
Scores: 2, 0, 4, 2
25. For the following scores, what is 2X +1? a. 9 bo
Scores: 2, 0, 4, 2
C72
d. 36 Answer c page 22
26. For the following scores, what is £(X + 1)? a. 9 oa ream We d. 3(9)= 36
Scores: 2, 0, 4, 2
Answer b page 21
27. How would the following mathematical operation be expressed in summation notation? "Subtract one point from each score and find the sum ofthe resulting values." oe 2) e | : = 1) 1 - xX One! Ba . U1 - X) 28. How would the following mathematical operation be expressed in summation notation? "Add two points to each score, square the resulting value, then find the sum of the squared numbers."
re
be,te es
b. GF 2y 6 2K +2)
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ae
Chapter 1: Exam Items - page 6
True/False Questions False page 4
1. A summary value, usually numerical, that describes a sample is called a parameter.
True page 3
2. A researcher is interested in the vocabulary skills of 3-year-old children. For this researcher, the entire set of 3-year-old children would be the population.
False
page 3
3. A researcher interested in human memory selects a group of 30 students to participate in a research study. The group of 30 students would be considered a population.
True page 5
4. The goal of descriptive statistics is to simplify, summarize, and organize data.
True page 10
5. To establish a cause-and-effect relation between two variables, a researcher
should use the experimental research method.
page 9
6. The correlation research method requires manipulation and control of variables to establish a relationship.
False
7. In the experimental method, the researcher manipulates the dependent variable.
False
page 11 True page 11
8. A recent report concluded that subjects assigned to a regular exercise program had fewer problems with depression than subjects who were not allowed to exercise regularly. For this study, depression is the dependent variable.
False page 14
9. The reading ability of 2nd-grade students is classified as high, medium, or low.
False
10. Last week the three major networks were ranked as follows: CBS first, NBC second, and ABC third. This is an example of measurement on a nominal scale.
page 15 True page 14 True
page 15
This classification involves measurement on a nominal scale.
11. Determining the favorite color for each child in a pre-school class would be an example of measurement on a nominal scale. Measurements from a nominal scale can be used to determine whether two individuals are the same or different, but cannot determine the direction or the size 12.
of the difference.
False
page 15
13. Ifa researcher measures two individuals on an ordinal scale, it is impossible to determine which individual has the larger score. Chapter 1: Exam Items - page 7
True page 17
14. Determining the favorite color for each child in a pre-school class would be an example of measurement of a discrete variable.
True page 17
15. Reaction time is an example of a continuous variable.
True page 17
16. A researcher records the sex of each child born in the county hospital during the month of June. This researcher is measuring a discrete variable.
False page 20
17. In statistical notation, a lower-case letter n is used to identify the number of scores in a population.
False page 21
18. To compute 2X + 3, the first step is to add 3 points to each of the original scores.
False page 21
19. To compute DX’, you first sum the scores and then square the total.
False
20. For any set of scores, DX? = (ZX).
page 21
False page 22
21. To compute U(X + 2)’, you first add 2 points to each score, then sum the resulting values, and finally you square the sum.
False page 23
22. For the following scores, 2X +1=10.
False page 22
23. For the following scores, U(X + 1)?=100.
False page 21
24. For the following scores, (2X)’=30.
True
25. For the following scores, UX? = 30.
Scores: 1, 0, 2,3
Scores: 1, 0, 2,3
Scores: 1, 2, 3, 4
Scores: 1, 2, 3, 4
page 21
Chapter 1: Exam Items - page 8
Other Exam Items 1. Statistical techniques are classified into two major categories: descriptive and inferential. Describe the general purpose of each category.
2. Define the concept of "sampling error." Note: Your definition should include the concepts of sample, population, statistic, and parameter. 3. Describe the sequence of mathematical operations that would be used to evaluate each of the following expressions. a. LX°
b. (aX) Go Ao 1 d. BCX + 1)
e. U(X +1) 4.
Calculate each value requested for the following set of scores.
Scores:
1, 2, 0, 4
a. UX be 2X?
6c (Ky 5.
Calculate each value requested for the following set of scores. a. Us 2
By
tia
e.
3(X+2y
Scores:
0, 1, 4, 2
2)
6. Calculate each value requested for the following set of scores. ee ve.8 ee b. -2Y 1 3 c. BADY 3 ] da. LAY i az 2 -4
Answers for Other Exam Items 1. The purpose of descriptive statistics is to simplify the organization and presentation of data. The purpose of inferential statistics is to use the limited data from a sample as the basis for making general conclusions about the population.
Chapter 1: Exam Items - page 9
2. A parameter is a value that is obtained from a population of scores and is used to describe the population. A statistic is a value obtained from a sample and used to describe the sample. Typically it is impossible to obtain measurements for an entire population, so researchers must rely on information from samples; that is, researchers use statistics to obtain information about
unknown parameters. However, samples provide only limited information about their populations. Thus, sample statistics are usually not identical to their corresponding population parameters. The error or discrepancy between a statistic and the corresponding parameter is called sampling error. 3. a. To compute 2X’, you first square each score, then sum the squared values.
b. To compute (ZX)’, you first sum the scores, then square the sum. c. To compute £X + 1, you first sum the scores, then add 1 to the sum. d. To compute X(X + 1) you first add 1 to each score, then sum the resulting values. e. To compute X(X + 1)’, you first add 1 to each score, then square the resulting values, then sum the squared numbers. 4. a. 7
b21 c. (7% =49 Siew
eae,
b. 15 c. 65 6. a. 6
b. -2 c. -12
d. -2
Chapter 1: Exam Items - page 10
Chapter 2 Frequency Distributions
Multiple-Choice Questions
Questions 1 through 3 concern the following table. x t 3 1 4 2 3 4 2 ] ] 2 1. For these data, N = Ce b. 10 c. 29 d. cannot be determined from the table
2. For these data, XX is a. 10
bes ce) 29 d. cannot be determined from the table
3. The proportion associated with X = 3 is a. 0.10 b. 0.20 ¢.. 0:30 d. 0.40 4. What is the shape of the distribution for the following set of data? Seorex:
1. 1, 1,2. 2.3.3.3
a. symmetrical b. positively skewed c. negatively skewed d. cumulative
Chapter 2: Exam Items - page 1]
5. What is the shape of the distribution for the following set of data? Scores:
1, 2, 2.2, 2, 3; 3, 4, 5,6
.
a. symmetrical b. positively skewed c. negatively skewed d. cumulative Answer c
page 37
6, Ina grouped frequency distribution one interval is listed as 50-54. What are the real limits of this interval? a. 50 and 54 b. 50.5 and 54.5 c. 49.5 and 54.5 d. 50.5 and 53.5 7. Ina grouped frequency distribution one interval is listed as 50-54. What is the width of this interval? a. 3 points b. 4 points c. 5 points d. 54 points 8. Frequency distribution polygons are intended for use with a. either interval or ratio scales of measurement b. only ratio scales c. either nominal or ordinal scales d. only nominal scales
9. A distribution of scores is being organized in a grouped frequency distribution table with an interval width of 2 points. If the lowest score in the distribution is X = 41, then the bottom interval in the table should be
a. 40-42
b. 41-43 c. 40-41 d. 41-42
10. Which of the following statements is false regarding grouped frequency distribution tables? a. An interval width should be used that yields about 10 intervals. b. Intervals are listed in descending order, starting with the highest value at the top of the X column. c. The bottom score for each interval is a multiple of the interval width. d. The value for N can be determined by counting the number of intervals in the X column.
Chapter 2: Exam Items - page 12
Answer c page 36
11. Ina frequency distribution graph, frequencies are presented on the ___ and the scores (categories) are listed on the __. X axis, Y axis horizontal line, vertical line Y axis, X axis oP class interval, horizontal line Be
Answer b page 42
12. Ina distribution with positive skew, scores with the highest frequencies are a. on the right side of the distribution b. on the left side of the distribution c. in the middle of the distribution d. represented at two distinct peaks Questions 13 through 15 refer to the following table showing a frequency distribution of quiz scores.
» ae i
me N hh WOW NO DN Wan
Answer c page 31
13. How many individuals took the quiz? as Beas ona
d. cannot be determined from the information given Answer C page 31
14. Ifa score of X = 3 or higher is needed for a passing grade, how many individuals passed? a. 3 b. 11 c 16 d. cannot be determined from the information given
Answer b page 31
15. How many individuals had a score of X = 2? a. | b, 3 eS d. cannot be determined from the information given
Chapter 2: Exam Items - page 13
Questions 16 through 18 refer to the following table showing a frequency distribution of exam scores.
xX 70-74 65-69 60-64 55-59 50-54 45-49 Answer b page 35
f 3 4 8 2 1 1
16. This is a grouped frequency distribution table where the scores have been grouped into class intervals using an interval width of a. 4 points b. 5 points c. 9 points d. 10 points
Answer d page 35
17. The lowest score on the exam is a. X =45 b. X= 49 CX =475 d. cannot be determined from the information given
Answer b page 35
18. For this set of exam scores, how many students had scores less than X = 60? rgd b. 4 bu 8 d. cannot be determined from the information given
Questions 19 through 22 refer to the following graph showing a frequency distribution of quiz scores.
PNW
Chapter 2: Exam Items - page 14
Answer b page 37
19. This graph is an example of a a. bar graph b. histogram c. polygon d. none of the above
Answer b
page 37
20. For this distribution, how many individuals had a score of X = 4? an
bo 2 c. 4
d. cannot be determined from the information given Answer b page 37
21. How many individuals took the quiz? a> b. 10 6. 30 d. cannot be determined from the information given
Answer d
22. What is the value of ©X for the entire set of scores shown in this distribution? a. 5 iy [5 =) aes
page 37
Questions 23 through 25 refer to the following graph showing a frequency distribution of quiz scores.
4
|
ee wi, ih x
A
Answer b
page 42
Z
3
23. Thisisanexample ofa —_ a. symmetrical
4
5
6
distribution.
b. positively skewed c. negatively skewed d. normal
Chapter 2: Exam [tems - page 15
Answer ¢ page 37
24. How many individual scores are represented in this graph? (What is the value of N?) a. 5
b. 6 er 3
d. cannot be determined from the information given Answer a
25. The lowest score in the class was X =
page 37
this score is
and the number of people with
True/False Questions True page 30
1. The purpose for constructing a frequency distribution table is to get an organized view of the entire set of scores.
True page 30
2. A professor recorded the academic major for each student in an introductory psychology class. If these data were organized in a frequency distribution table, the first column would be a list of academic majors.
True page 31
3. When listing scores in a frequency distribution table, you should not skip any
False page 31
4. Ina frequency distribution table, N can be obtained by counting the number of values listed in the X column.
True page 31
5. For any frequency distribution table, N = Uf.
False page 31
6. Ina frequency distribution table, the 2X may be obtained by simply adding the values in the column labeled X.
True page 32
7. Proportions can be obtained for each interval in a frequency distribution by computing p = f/N.
True page 33
8. In a sample of n = 30 scores, the lowest score is K = 15 and the highest score is X = 44. Ifthe scores are put in a frequency distribution table, then a grouped
scores, even if one has a frequency of zero.
table should be used.
Chapter 2: Exam Items ~ page 16
False page 33
9. As a general rule, a grouped frequency distribution table should have approximately 15 to 20 class intervals.
True page 34
10. Ina grouped frequency distribution table, all of the class intervals should have exactly the same width.
False page 33
11. You should use a grouped frequency distribution table whenever there are more than 15 or 20 scores in the distribution.
True page 35
12. Ina grouped frequency distribution, a class interval listed as 10-19 has an interval width of 10 points.
True page 31
13. There is enough information in a regular frequency distribution table to obtain a complete listing of the original set of scores.
False page 35
14. There is enough information in a grouped frequency distribution table to obtain a complete listing of the original set of scores.
True page 34
15. Ina grouped frequency distribution table, the bottom value in each class interval should be a multiple of the interval width.
False page 34
16. For a grouped frequency distribution table, a class interval should be omitted from the table if there are no scores in the interval.
True page 36
17. Ina frequency distribution graph, the frequency values are presented on the vertical axis and the scores (or measurement categories) are presented on the horizontal axis.
True page 37
18. Bar graphs may be used for data that are measured on a nominal or an ordinal scale.
True page 39
19. A professor records the academic major for each student in a class. If these data are presented in a frequency distribution graph, the graph should not be a polygon.
True page 39
20. A professor records the height (in inches) for each student in a class. If these data are presented in a frequency distribution graph, it would be acceptable to use a polygon.
False
page 37
21. A frequency distribution histogram is best suited for data measured on a nominal scale.
True page 39
22. You should not use a polygon to display a distribution of scores that have been measured on a nominal scale.
Chapter 2: Exam Items - page 17
True
23. It would be acceptable for the data in a histogram to be re-drawn in a polygon.
page 39
False
24. A histogram is drawn so that there are spaces between the bars.
page 37
True
25. A negatively skewed distribution has a tail on the left side of the graph.
page 42
True page 42
26. Ina positively skewed distribution, the scores tend to pile up on the left-hand side of the graph.
False
27. When the scores pile up on the right-hand side of a distribution and taper off
page 42
to the left, then the distribution is positively skewed.
True page 42
28. The scores for a very easy exam would probably form a negatively skewed distribution.
Other Exam Items 1. Briefly explain when and why you should use a grouped frequency distribution table instead of a regular table. 2. Briefly explain what information is available in a regular frequency distribution table that is not available in a grouped table.
3. For the following data, construct a grouped frequency distribution table. Include columns for proportion, and percent. 41 32 67 44 46 47 36 53 56 45 31 43 25 33 25 38 48 57 42 49 4. For the following quiz scores, sketch a histogram of the frequency distribution. 5 2 10°9 7 ©: 10 1837 34-19 OP atT a Ben
Chapter 2: Exam Items - page 18
5. Answer each question for the following data. Zo 37 Ais td) a 0 13 P9521 49 37) 29 20 16-17 34 16 35 24 16 12 29 30 a. Which is more appropriate, a regular or a grouped frequency distribution table? Explain why. b. Construct the appropriate table. c. Based on the table, what is the shape of the distribution?
6. For the following data, construct a grouped frequency distribution table using an interval width of 10. Include columns for proportion and percent. 30 22 58 28 35 67 27 42 46 35 OL -3a 18.33 20 38 48.30.31 39
Answers for Other Exam Items 1. You should use a grouped table whenever the range of scores is too wide to list each value in a regular table. Usually, a range of more than 15 points will require a grouped table. 2. A regular table identifies each individual score exactly. However, in a grouped table, you simply know that an individual score is located in a particular interval; you do not know its exact value. a
xX 6-69 60-64 s-59 50-54 45-49 40-44 35-39 30-34 23-29
f 1 0 2 1 5 4 2 3 2
Pp 0.05 0 0410 0.05 0.25 0.20 0.10 O15 0.10...
% 5% 0% . 10% 5% 25% 20% 10% 15% 10%
Chapter 2: Exam Items - page 19
Fh
PNM oOo We
5. a. A grouped frequency distribution table would be better. The lowest score is X = 12 and the highest is X = 49. A regular table would require 38 rows. b.
x 45 - 49 40 - 44 20 oo 30 - 34 Za 22 20 - 24 15-19 10-14
WHA WLR BW S| W
c. The distribution is positively skewed.
a
nak 60-69 S059 40-49 30-39 20-29 i=1o
Hf 1 924 3 9 4 1
Pp 0.05 010, O15 045 0.20 9:05
% 5% 10% 15% 45% 20% 5%
Chapter 2: Exam Items - page 20
Chapter 3 Central Tendency Multiple-Choice Questions Answer d
1. What is the value of the mean for the following set of scores?
page 53
eoores: 1) 3,5, 0, 1
a, 10 3 or 2 a2
www
Answer C page 53 WWW
Answer a
page 53
Answer a
page 57
2.
A sample of n=5 scores has a mean of X = 9. What is UX for this sample? a. 9/5 = 1.80 b. 5/9 =0.555 c. 3(9)=45 d. cannot be determined from the information given
3. A population of scores has 2X = 60 and a mean of = 12. How many scores are in this population? ra) b 12 c. 60 d. cannot be determined from the information given
4. A sample has a mean of X = 42. Ifa new score with a value of X = 50 is added to the sample, what effect will it have on the sample mean? a. The sample mean will increase. b. The sample mean will decrease. c. The sample mean will remain the same. d. cannot be determined from the information given 5. A sample has a mean ofX = 30. If one score with a value of X = 10 is removed from the sample, what effect will it have on the sample mean? a. The sample mean will increase. b. The sample mean will decrease. c. The sample mean will remain the same. d. cannot be determined from the information given
Chapter 3: Exam Items - page 21
6. A sample has a mean of X = 25. Ifa new score with a value ofX = 25 is added to the sample, what effect will it have on the sample mean? a. The sample mean will increase. b. The sample mean will decrease. c. The sample mean will remain the same. d. cannot be determined from the information given 7. Asample of n= 25 scores has a mean of X = 11. Ifeach score in the sample is multiplied by 6, the new mean would be
a. 6 b. 11 Cruly d. 66 Answer a
page 59
8. After 5 points are added to every score in a distribution, the mean is calculated and found to be » = 30. What was the value of the mean for the original distribution? Fee)
b. 30 C35 d. cannot be determined from the information given
Answer d page 59
9. Which of the following is a property of the mean? a. Changing the value of a score will change the value of the mean. b. Adding a constant to each score will add the same constant to the mean. c. Multiplying each score by a constant will multiply the mean by the same constant.
d. all of the above Answer b
page 57
10. A set of N = 20 exam scores has a mean of p = 50. The instructor discovered that one student cheated on the exam so 20 points are subtracted from that student's score. What is the new mean for the class? a. 50 b. 49 oe: 30 d. cannot be determined from the information given
Answer a
11.
page 57
Which measure(s) of central tendency is (are) certain to be changed? a. the mean ; b. the median c. the mean and the median d. the mode
The value of one score in a distribution is changed from X = 20 to X = 30.
Chapter 3: Exam Items - page 22
12. One sample of n= 4 scores has a mean of X = 10, and a second sample of n = 8 scores has a mean of X = 20. Ifthe two samples are combined, the mean for the
combined sample will be
;
a. equal to 15 b. greater than 15 but less than 20 c. less than 15 but more than 10 d. none ofthe above Answer a
page 57
Answer c
page 54
Answer c
page 54
13. A sample of n = 20 scores has a mean of X = 55. After one score is removed from the sample, the mean for the remaining scores is found to be X = 51. From this information you can conclude that the removed score was a. greater than 55 b. less than 55 c. It is impossible to estimate the magnitude of the score. 14. Ina population of N = 6, five of the individuals all have scores that are exactly 1 point above the mean. From this information you can determine that the score for the sixth individual must be a. also above the mean by | point b. below the mean by one point c. below the mean by 5 points d. not enough information to describe the 6th score 15. Ina sample of n= 3 scores, the first person has a score that is below the mean by 2 points and the second person is below the mean by 4 points. Which of the following provides the most accurate description of the score for the third person? a. It is above the mean. b. It is above the mean by an average of 3 points. c. It is above the mean by 6 points. d. The score cannot be described based on the information given. 16. What is the median for the following set of scores?
Scores:
1, 3, 9, 10, 22
Scores:
1, 4, 6, 17
a. 6
b. 9 C.2
ae
Answer b page 61
17. What is the median for the following set of scores? a. 4
ae hn QR SI
Chapter 3: Exam Items - page 23
18. A teacher gave a reading test to a class of Sth-grade students and computed the mean, median, and mode for the test scores.
Which of the following statements
cannot be an accurate description of the scores? a. The majority of the students had scores above the mean. b. The majority of the students had scores above the median. c. The majority of the students had scores above the mode. d. All of the above must be false statements. Answer C
page 63
Answer a
page 70
Answer a
page 70
Answer c
page 71
Answer c
page 67 www
19. A distribution can have more than one mean . median mode . none of the above of ao
20. For a distribution of scores, the mean is equal to the median. This distribution is most likely to be a. symmetrical b. positively skewed c. negatively skewed d. impossible to determine the shape 21. Fora perfectly symmetrical distribution with p = 30, the median would have a value : . equal to 30 . greater than 30 . less than 30 . cannot be determined from the information given fm aot
22. For a positively skewed distribution with = 30, the median would have a value ; equal to 30 . greater than 30 . less than 30 . cannot be determined from the information given of uo 23. A set of individuals is measured on a nominal scale. To determine the central tendency for the resulting measurements, a researcher should use the a. mean b. median c. mode d. It is impossible to determine central tendency for nominal measurements.
Chapter 3: Exam Items - page 24
Answer b page 71
24. A distribution is positively skewed. three measures of central tendency? a. mean b. mean c. mean d. mean
= 40, median = 60, median = 40, median = 50, median
= 50, mode = 50, mode = 60, mode = 50, mode
Which is the most probable order for the = 60 = 40 = 50 = 50
25. Ina negatively skewed distribution of exam scores, Tom scored at the mean, Mary scored at the median, and Jane scored at the mode. Who had the highest score? a. Tom b. Mary c. Jane
d. cannot be determined from the information given Answer c page 62
26. For any distribution, you can be sure that at least one individual has a score equal to the a. mean b. median c. mode d. all of the above 27. For an extremely skewed distribution of scores the best measure of central tendency would be the a. mean b. median c. mode d. Central tendency cannot be determined for a skewed distribution.
True/False Questions True page 51
1. One purpose for central tendency is to find a single score that can serve as a representative value for an entire distribution.
True page 5]
2. One purpose for central tendency is to describe the location of the center of an entire distribution of scores.
False page 53
3. Last summer I had three monthly phone bills of $20, $30, and $100. My mean phone bill for the summer was $75. Chapter 3: Exam Items - page 25
True page 53
4. A sample of n= 6 scores has a mean of X =8. The scores in the sample must sum to £X = 48.
True
page 59
5. A population has p = 40. If 5 points are added to every score, the mean will be . changed to p = 45.
False page 59
6. Adding a constant amount to every score in a population will not change the value of the mean.
True page 59
7. After each score in a population is multiplied by 3 the mean is found to be 1 = 90. Based on this information, you can conclude that the original mean was i= 30;
False page 71
8. A sample of n= 10 scores will always have five scores below the mean and five scores above the mean.
False page 54
9. The mean is considered to be the “balance point” for a distribution because exactly have the scores exactly half of the scores are located above the mean and exactly half are below the mean.
True page 71
10. It is possible for more than half of the scores in a distribution to have values greater than the mean.
False
page 60
11. It is possible for more than half of the scores in a distribution to have values greater than the median.
False page 71
12. A distribution with a mean p: = 50 and a median of 70 probably is positively skewed.
True page 65
13. Inaskewed distribution, the mean is often displaced toward the tail so that it is not a good, representative measure of central tendency.
True
14. Ifa negatively skewed distribution has a mean of 50, then the mode is probably greater than 50.
page 71 True page 63
15. A distribution can have more than one mode.
True page 67
16. It is impossible to compute the mean for data that have been measured on a nominal scale. :
False page 67
17. It is impossible to measure central tendency for data that have been measured on a nominal scale.
Chapter 3: Exam Items - page 26
True page 70
18. In a symmetrical distribution, the mean is equal to the median.
False page 73
19. Ona 50-point exam Tom has a score of X = 23. This means that Tom scored below the median.
False page 63
20. In addition to having two modes, a bimodal distribution typically has two medians.
True page 71
21. For a positively skewed distribution, the mean tends to have a larger value than either the median or the mode.
True page 65
22. Extreme scores in a distribution are more likely to affect the value of the mean than the value of the median.
True page 55
23. If one sample with a mean of X = 10 is combined with a second sample with a mean of X = 20, then the mean for the combined sample will be between 10 and 20.
True page 67
24. The mode is the best way to measure central tendency for data from a nominal scale.
True page 68
25. Ina published report of research results, a sample mean is typically identified by the letter M.
True page 68
26. Ina graph showing the relation between an independent variable and a dependent variable, the values of the independent variable are displayed on the horizontal axis.
Other Exam Items
1. What is the purpose for obtaining a measure of central tendency?
2. Explain why it is necessary to have more than one standard procedure for defining and measuring central tendency. Chapter 3: Exam Items - page 27
3. Describe two circumstances where the median would provide a better measure of central tendency than the mean. 4. Although it was not discussed in the textbook, describe what happens to the median and the mode when a constant is added to every score in a distribution. 5. Find the mean, the median, and the mode for the set of scores in the frequency distribution table below. xX 5 4 3 2 1 6.
f 2 3 2 2 1
Mean
=
Median
=
Mode =
Find the mean, the median, and the mode for the set of scores in the frequency distribution
histogram below.
4
Mean
=
3
Median
=
2
Mode
=
e
7. A-set ofn=7 scores has a mean of X = 10. Another set of scores has n = 3 and X = 20. If these two sets of scores are combined, what is the mean for the combined group?
8. A sample of n= 5 scores has a mean of X = 8. If one score with a value ofX = 4 is removed from the sample, what is the mean for the remaining scores?
9. A sample of n= 5 scores has a mean of X = 10. One new score is added to the sample and the new mean is computed to be X = 11. What is the value of the score that was added to the sample?
Chapter 3: Exam Items - page 28
Answers for Other Exam Items
1. The purpose of a measure of central tendency is to find the single score that identifies the middle of the distribution and best represents the entire distribution.
2. No single method for measuring central tendency will produce a good, representative value in every situation. 3. a. When there are extreme scores (skewed distribution) b. When there are undetermined scores. c. When there is an open-ended distribution d. When the data are measured on an ordinal scale
4. When you add a constant to every score, the entire distribution is shifted to a new location. All of the individual scores are shifted, and the mean, median, and mode move along with the whole distribution.
5. Mean = 33/10 = 3.30.
Median=3.5.
Mode =4.
6. Mean = 27/10 =2.70.
Median=2.5.
Mode =2.
7. For the combined sample, n = 10, 2X = 130, and Gees
8. The original sample had n = 5 scores with 2X = 40. When the score is removed, there are n= 4 scores with 2X = 36. The new mean is X = 9. 9. The original sample had n= 5 scores with YX = 50. After the new score is added, there are n= 6 scores with YX = 66. Because the sum increased by 16 points, the new score must be m= 16.
Chapter 3: Exam Items - page 29
Chapter 4 Variability
Multiple-Choice Questions Answer c
page 78
Answer d page 81
1. Ina population of N = 10 scores, the smallest score is X = 8 and the largest score is X = 20. The range for the population is art b. 12 e. 13 d. cannot be determined without more information
2. Which of the following deviation scores corresponds to the score that is farthest away from the mean? a. 0 by 5 (a)
d. -10 Answer b page 81
3. Ina population with a mean of p = 50, a score of X = 45 would have a deviation score of a. 5 b. -5 c. 45
d. cannot be determined without more information Answer b
page 83
4. The symbol SS stands for the a. sum of squared scores b. sum of squared deviations c. sum of scores, squared d. sum of the deviations, squared
5. A population of N = 5 scores has SS = 40. What is the variance for this
population? a. 40/5 =8 b. 8° = 64 c. 40/4 = 10 d. 10° = 100
Chapter 4: Exam Items - page 30
6. A sample of n=5 a. 40/5 =8 b. 8° = 64 c. 40/4 = 10 d. 10?=100
scores has SS = 40. What is the variance for this sample?
7. Sample variance is identified by the symbol Ass
as Go
ds Answer ¢
page 85
8. Population standard deviation is identified by the symbol a. S
b. s c. o
dog Answer a
page 85
9. A population has SS = 30 and co”? = 6. What is the number of scores in the population? a N=9d by M6 ¢. W180 d. cannot be determined without additional information
10. What is the relationship between the standard deviation and variance? a. Standard deviation equals the variance divided by N. b. Standard deviation equals the variance divided by n - 1. c. Variance is the square root of standard deviation. d. Standard deviation is the square root of variance. 11. A population of scores has yp = 50 and o = 12. If you subtract five points from every score in the population, then the value for the new standard deviation will be a7 b. 12 Ge 24 d. insufficient information, cannot be determined Answer Cc
12. A population has p = 40 and o = 8. If each score is multiplied by 2, the new
page 97
standard a. b. & d.
deviation will be 4 8 16 insufficient information, cannot be determined
Chapter 4: Exam Items - page 31
Answer b
page 96
13. A population of scores has p = 20 and o = 5. If two points are added to every score in the population, then the new values for the mean and standard deviation would be a. w= 20 ando=5 b, w= 22 ando=5 ¢. p=20ando=7 d. w=22 ando=7 14. A population of scores has p, = 20 and o = 5. If every score in the population is multiplied by 2, then the new values for the mean and standard deviation would a b. p=40 ando=5 c. p= 20 ando=10 d. p= 40 ando=10
Answer c
15. To compute sample variance, the value of SS is divided by
page 89
Answer a
page 88
the variability of 16. The variability of the scores in a sample tends to be the scores in the population from which the sample was obtained. a. smaller than b. larger than c. exactly the same as 17. Sample variance provides an unbiased estimate of the population variance. The term unbiased means _ : a. for any sample, the sample variance will equal the population variance b. for large samples, the sample variance will equal the population variance c. if sample variance is computed for many samples, the average of all the sample variances will equal the population variance d. none of the above
Answer c
page 94
18. Which of the following sample statistics does not provide an unbiased estimate of the corresponding population parameter? a. the sample mean b. the sample variance c. the sample standard deviation
Chapter 4: Exam Items - page 32
Answer b
page 80
19. You must determine Q1 and Q3 to compute the ___.
a. sum of squared deviations b. semi-interquartile range c. variance d. standard deviation
Answer a
20. Ifa population has a mean of
page 82
avalueof a. 0 b. 16
= 24 with o = 4 and N = 10, then X(X - 1) has
op 25
d. 400 Answer a
page 88
21. A sample of n= 8 scores has SS = 50. If these same scores were a population, then the SS value for the population would be a. 50 b. greater than 50 c. less than 50 d. impossible to determine without additional information 22. What is the value of SS for the following set of scores? a. 144 bi. 62 c. 14 d. none of the above
S2O.0h:
23. For the population of scores 5 2 5 4, the variance equals a. 6 be Z
Answer e
page 82
24. Which of the following samples would have the largest value for sample variance? a.
1.3.0
&, 11, 13,15 & DLS 559 ad) 101, 103, 105 e. All the samples would have exactly the same variance.
Chapter 4: Exam Items - page 33
25. Which set of scores has the least amount of variability? GO U es poe: SAG eee RLF 143, 145, 145, 147 . 40, 27, 805105 fa0 26. Which set of parameters would make X = 85 an extreme score in the distribution? a. w= 80 ando=5 b. up = 80 and o = 20 c. p= 70ando=5 d. p= 70 and o = 20 Answer ¢ page 94
27. The smallest score in a population is X = 5 and the largest score is X = 10. Based on this information, you can conclude that a. the population mean is somewhere between 5 and 10. b. the population standard deviation is smaller than 6 c. all of the above d. none of the above
Answer b
28. For a particular sample, the largest distance (deviation) between a score and the mean is 11 points. The smallest distance between a score and the mean is 4 points. Therefore, the standard deviation . must be less than 4 must be somewhere between 4 and 11 . must be greater than 11 & . It is impossible to say anything about the standard deviation. aow
page 90
29. If you have a score of X = 75 on an exam, which set of parameters would give you the highest position within the class? a. p= 70ando=5 b. p= 70 ando= 15 c. p= 60 ando=5 d. w= 60 ando=15
True/False Questions True
page 79
1. The range is generally considered to be a relatively crude way to measure variability.
Chapter 4: Exam Items - page 34
True page 81
2. A negative deviation always indicates a score that is less than the mean.
True page 82
3. For any population of scores, the sum of the deviations will be equal to zero.
False page 83
4. SS is the sum of the squared scores.
True page 83
5.
True page 81
6. A deviation of zero corresponds to a score exactly equal to the mean.
True page 89
7. Ifa sample has a variance of 16, then the sample standard deviation is 4.
True
page 96
8. Ifaconstant is added to every score in a distribution, then the standard deviation will remain unchanged.
False page 96
9. A population has p = 20 and o = 5. If five points are added to every score in the population, the new set of scores will have o = 10
True page 97
10. If every score in a population is multiplied by 3, then the population standard deviation will also be multiplied by 3.
True
11. The scores in a sample tend to be less variable than the scores in the population from which the sample was obtained.
page 88 True
page 86
When calculating SS, it is impossible to obtain a value less than zero unless a
mistake is made.
12. The value for the standard deviation cannot be larger than the value for the range.
False page 83
13.
For any distribution, L(X - 1)’ will always equal zero.
False
14. A sample of n= 5 scores has SS = 20. The variance for this sample is 4.
page 89
15. A population of N = 5 scores has SS = 20. The variance for this population
True page 85
is 4.
True page 94
16. Ina distribution with p = 40 and o = 2, a score of X = 46 would be considered an extreme value (far out in the tail). Chapter 4: Exam Items - page 35
distribution with p = 40 and o = 12, a score of X = 46 would be
False
17. Ina
page 94
considered an extreme value (far out in the tail).
True
18. Ina
page 86
is X = 35. For this distribution, the standard deviation cannot be greater than 5.
True page 94
19. Ifa distribution has p = 20 and o = 1, you can be confident that the majority of the scores are located between 18 and 22.
True page 81
20. The standard deviation provides a description of the average distance from the mean.
True page 88
21. For a specific set of scores, the value you obtain for SS will be the same whether the set of scores is a sample or a population.
False page 85
22.
True page 89
23. By using n- | in the formula for sample variance, you will get an unbiased estimate of population variance.
False page 92
24. When a sample statistic is said to be “unbiased” it means that the value of the statistic will always be equal to the corresponding population parameter.
‘rue page 85
25. For a population, variance is the mean of the squared deviation scores.
False page 96
26. Large sample variance makes it easier to see means and mean differences in sample data.
distribution with p = 40, the largest score is X = 45 and the smallest score
When computing the population variance, SS is divided by n-
1.
Other Exam Items 1. For the following set of data, find the range and the semi-interquartile range. scores:
3,.5, 3,.2, 604, 6, 7,1, 4; 3,2
2. For the following set of data, compute the value forSS.
Scores:
Chapter 4: Exam Items - page 36
5 2 2 7 9
3. For the following population of scores, use the definitional formula (the definition) to compute SS. Then compute the variance and the standard deviation for the population. Scores: 9 1 8 6 4. For the following sample, use the computational formula to calculate SS. Scores: 1, 7, 1, 1 sample variance and standard deviation.
Then, compute the
5. Calculate the variance and standard deviation for the following sample data. mcoress, 2°93) 2-457 (5-30 6 4
6. A distribution of N = 10 scores has p = 50 and o = 10. If another five individuals, all with scores of X = 50, are added to this distribution, what will happen to the standard deviation?
Will
it increase, decrease, or stay the same? Explain your answer.
7. Without some correction, sample variability is said to be "biased." Define the term biased, and explain how this bias is corrected in the formula for sample variance.
Answers for Other Exam Items 1. The range is 8 points and the semi-interquartile range is (5.5 - 2.5)/2 = 1.5 points. 2. so = 38 3. SS=38;
0° =9.5;
o=3.08
4, §S=27;
# =9: s=3
5. SS=24;
s*=3;s=1.73
6. The variability will decrease. Adding new scores at the mean will not change the mean, but it does result in more scores being clustered at the mean. As a result the standard deviation (average distance from the mean) will decrease. 7. On average, sample variability is less than population variability. Whenever a statistic consistently underestimates (or overestimates) the corresponding population parameter, the statistic is said to be biased. The bias in sample variability is corrected by dividing by n - 1 (instead of n) in the formula for sample variance.
Chapter 4: Exam Items - page 37
Chapter 5 z-Scores
Multiple-Choice Questions
Answer d page 106 www
1. A z-score of z = -2.00 indicates a position in a distribution a. above the mean by 2 points b. above the mean by a distance equal to 2 standard deviations c. below the mean by 2 points d. below the mean by a distance equal to 2 standard deviations
Answerd page 107
2. Of the following z-score values, which one represents the most extreme location on the left-hand side of the distribution? a. z=+1.00 b. z= +2.00 c. z=-1.00 d. z= -2.00
Answer a page 108
3. For a population with p = 80 and o = 10, the z-score corresponding to X = 85 : would be +0.50 +1.00 +2.00 aos or o.00
Answerb page 108
4. For a population with : = 80 and o = 10, the z-score corresponding to X = 70 would be : a. -10 b. -1.00 go 00 ds +10
Chapter 5: Exam Items - page 38
Answer b page 109
5. For a population with 1 = 60 and o = 8, the X value corresponding to z= -0.50 would be a. -4
b. 56 c. 64 dP S9S Answer c
page 109 www
Answer c page 106 Www
6. Fora population with p = 60 and o = 8, the X value corresponding to z= 1.50 would be H.. TZ age oy We 6. 72 d. 90
7. A population of scores has pp = 44. In this population, an X value of 40 corresponds to z= -0.50. What is the population standard deviation? ae 2 ni:2 cs d.6
Answer b
page 106
8. A population of scores has p = 50. In this population, an X value of 58 corresponds to z= 2.00. What is the population standard deviation? And b. 4 c: 8 d. 16
9. A population of scores has o = 20. In this population, a score of X = 80 corresponds to z = +0.25. What is the population mean? a. 70
Bb. 75 e. B35 d. 90 Answer c
page 106
10. A population of scores has o = 10. In this population, a score of X = 60 corresponds to z = -1.50. What is the population mean? a. -30 b. 45 ei)
d. 90
Chapter 5: Exam Items - page 39
11. Under what circumstances would a score that is 15 points above the mean be considered an extreme score? a. when the population mean is much larger than 15 b. when the population standard deviation is much larger than 15 c. when the population mean is much smaller than 15 d. when the population standard deviation is much smaller than 15 Answer c
page 106
Answer c
12. A very bright student is described as having an IQ that is three standard deviations above the mean. If this student's IQ is reported as a z-score, the z-score would be a ut 3 b. ut+3o0 rete) d. cannot be determined from the information given
13.
A z-score of z = +3.00 indicates a location that is a. near the center of the distribution b. slightly above the mean c. far above the mean in the extreme right-hand tail of the distribution d. The location depends on the mean and standard deviation for the distribution.
14.
A z-score of z = -0.25 indicates a location that is a. at the center of the distribution
page 107
Answer b
page 107
b. slightly below the mean c. far below the mean in the extreme left-hand tail of the distribution
d. The location depends on the mean and standard deviation for the distribution. Answer c
page 106
15. A population distribution has » = 80 and o = 6. In this distribution a z-score of z = +2.00 identifies a location a. two points above the mean b. two points below the mean c. twelve points above the mean d. twelve points below the mean
Answer c
page 106
16. For a population with o = 4, an individual with a deviation score of +2 would have a z-score of a. +2.00 b. +8.00 C.F -30 d. cannot be determined without knowing the population mean
Chapter 5: Exam Items - page 40
Answer a
page 112 www
Answer b
page 112
17. Suppose you earned a score of X = 54 onan exam. Which set of parameters would give you the highest grade? a. p =50 ando=2 b. up = 50 ando =8 c. h=58 ando=2 d. p=58 ando=8
18. Suppose you earned a score of X = 45 on an exam. would give you the highest grade?
Which set of parameters
a. w=50ando=2 b. p= 50 ando=10 GC. = S53 ando=2Z d. nu=55 ando= 10 Answer b page 112
19. Last week Tom had exams in statistics and in English. He scored 10 points above the mean on both exams. From this information, you can conclude that a. Tom has identical z-scores for the two exams b. Both of Tom's z-scores are positive c. Tom will have a higher z-score for the exam with the lower mean d. none of the above
Answer c
20. A population with p = 85 and o = 12 is transformed into z-scores. After the transformation, the population of z-scores will have a mean of
page 110
a. p= 85 b. un= 1.00 cj p= 0
d. cannot be determined from the information given Answer b
page 111
21. A population with p = 85 and o = 12 is transformed into z-scores. After the transformation, the population of z-scores will have a standard deviation of a. o= 85 b. o = 1.00 c. 6 =0
d. cannot be determined from the information given Answer d
page 106
22. For a symmetrical population with p = 100 the z-score corresponding to X = 120 would be a. 1.20 b. 2.00 e. 1.00
d. cannot be determined from the information given
Chapter 5: Exam Items - page 41
Answer d page 111 www
23. A population has p = 50 and o = 10. If these scores are transformed into z-scores, the population of z-scores will have ameanof___ and a standard deviationof _.. a. 50, 10
bo0et c. 0, 10
d. 0, 1 24. One advantage of transforming X values to z-scores is a. all negative numbers are eliminated b. the distribution is transformed to a normal shape c. all scores are moved closer to the mean d. all of the above e. none of the above
25. A distribution with p = 35 and o = 8 is being standardized so that the new mean and standard deviation will be 1 = 50 and o = 10. When the distribution is standardized, what value will be obtained for a score of X = 39 from the original distribution? a. X = 54 b. X = 55 c. X=1.10
d. impossible to determine without more information Answer b page 114
26. A distribution with p = 35 and o = 8 is being standardized so that the new mean and standard deviation will be p = 50 and o = 10. In the new, standardized distribution your score is X = 60. What was your score in the original distribution? a. b. c.
X =45 X = 43 X = 1.00
d. impossible to determine without more information Answer c
page 114
27. Using z-scores, a population with p = 37 and o = 8 is standardized so that the new mean is = 50 and o = 10. How does an individual's z-score in the new distribution compare with his/her z-score in the original population? a. new z= old z+ 13 b. new z= (10/6)(old z) c. newz=oldz d. cannot be determined with the information given
Chapter 5: Exam Items - page 42
True/False Questions True
1. A positive z-score always corresponds to a score greater than the mean.
page 106 True page 106
2. For any distribution, a z-score of z = -0.50 corresponds to a location below the
False page 110
3. Fora positively skewed distribution, a z-score of zero will be located below (to the left of) the mean.
True page 107
4. Within any distribution of scores, the location specified by z = +1 and the location specified by z = -1 are exactly the same distance from the mean.
True
5. For any population, a z-score of -2.00 indicates a more extreme location (farther from the mean) than a z-score of +1.00.
page 107 True
page 108
mean.
6. Ina distribution with p = 50 and o = 10, a score of X = 55 corresponds to a z-score of z= +0.50.
page 108
7. Ina distribution with p = 50 and o = 10, a score of X = 30 corresponds to a z-score of z= -3.00.
False page 108
8. Ina distribution with p = 80 and o = 20, a score of X = 85 corresponds to a zscore of z = 1.50.
True
9. Ina distribution with 1: = 80 and o = 20, a score of X = 100 corresponds to a zscore of z = 1.00.
False
page 108 False
page 109
10. Ina distribution with p = 40 and o = 12, a z-score of z= -0.50 corresponds to a score ofX = 46.
page 109
11. Ina distribution with p = 40 and o = 12, a z-score ofz = 2.00 corresponds to an X value of X = 64.
False page 106
12. For any population, a z-score of +1.00 corresponds to a location exactly 1 point above the mean.
True page 106
13. For any population, a z-score of +1.00 corresponds to a location above the mean by one standard deviation.
True page 106
14. Ina distribution with p = 80, a score of X = 90 corresponds to z = +2.00. The standard deviation for this population is o = 5S.
True
Chapter 5: Exam Items - page 43
False page 106
15. Ina distribution with 1: = 80, a score of X = 70 corresponds to z = -0.50. The standard deviation for this population is o = 5.
False
16. Ina distribution with o = 8, a score of X = 64 corresponds to z = -0.50. The mean for this population is 1 = 60.
page 106
page 106
17. Ina distribution with o = 4, a score of X = 48 corresponds to z= 2.00 The mean for this population is p = 40.
True page 106
18. On an exam, Tom scored 8 points above the mean and had a z-score of +2.00. The standard deviation for the set of exam scores must be o = 4.
True page 112
19. On an exam with p = 70, you have a score of X = 76. In this situation you should expect a better grade if o = 3 than if o = 12.
False page 110
20. Transforming X values into z-scores makes it possible to describe an entire distribution with a single number.
False page 106
21. In any population of scores, at least one individual will have a z-score of zero.
False
22. Ifa population of N = 10 scores is transformed into z-scores, there will be five positive z-scores and five negative z-scores.
True
page 106
page 110
23. Ifa distribution of scores is transformed into z-scores then the sum of the positive z-scores will be exactly equal to the sum of the negative z-scores (ignoring the signs).
True
24. The population mean always corresponds to a z-score of zero.
True
page 110 True page 106
25. Iftwo individuals in a population have identical X scores, they also will have
True page 110
26. Transforming X values into z-scores will not change the shape of the distribution.
False page 110
27. One advantage of transforming X values into z-scores is that the transformation always creates a normal shaped distribution.
True
28. Whenever a population is transformed into z-scores, £z = 0.
identical z-scores.
page 110
Chapter 5: Exam Items - page 44