CHAPTER TEST MIDTERMS (PSYCH STATS)

Question 1

CHAPTER 5

1. What location in a distribution corresponds to z= -3.00?
   a. Above the mean by 3 points.
   b. Above the mean by a distance equal to three standard deviations.
   c. Below the mean by 3 points.
   d. Below the mean by a distance equal to three standard deviations.

Answer 1

d. Below the mean by a distance equal to three standard deviations.

Question 2

CHAPTER 5

2. For a population with m=90 and s=12, what is the z-score corresponding to X=102?
   a. +0.50
   b. +1.00
   c. +1.20
   d. +12.00

Answer 2

b. +1.00

Question 3

CHAPTER 5

3. For a sample with M= 72 and s= 4, what is the X value corresponding to z= -2.00?

a. X=70
b. X=68
c. X=64
d. X=60

Answer 3

c. X=64

Question 4

CHAPTER 5

4. In a population with m=70, a score of X=68 corresponds to a z-score of z=-0.50. What is the population standard deviation?
   a. 1
   b. 2
   c. 4
   d. Cannot be determined without additional information.

Answer 4

c. 4

Question 5

CHAPTER 5

5. In a sample with a standard deviation of s=4, a score of X=64 corresponds to z=-0.50. What is the sample mean?
   a. M=62
   b. M=60
   c. M=66
   d. M=68

Answer 5

c. M=66

Question 6

CHAPTER 5

6. In a population of scores, X= 50 corresponds to z= +2.00 and X= 35 corresponds to z= -1.00. What is the population mean?
   a. 35
   b. 40
   c. 37.5
   d. 45

Answer 6

b. 40

Question 7

CHAPTER 5

7. In a sample, X=70 corresponds to z= +2.00 and X=65 corresponds to z=+1.00. What are the sample mean and standard deviation?
   a. M=60 and s= 5
   b. M=60 and s=10
   c. M=50 and s=10
   d. M=50 and s=5

Answer 7

a. M=60 and s= 5

Question 8

CHAPTER 5

8. A population with m=90 and s= 20 is transformed into z-scores. After the transformation, what is the mean for the population of z-scores?
   a. m=80
   b. m=1.00
   c. m=0
   d. Cannot be determined from the information given.

Answer 8

c. m=0

Question 9

CHAPTER 5

9. A sample with a mean of M=70 and a standard deviation of s=15 is being transformed into z-scores. After the transformation, what is the standard deviation for the sample of z-scores?
   a. 0
   b. 1
   c. n=-1
   d. n

Answer 9

b. 1

Question 10

CHAPTER 5

10. Which of the following is an advantage of transforming X values into z-scores?
    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. Dissimilar distributions can be compared.

Answer 10

d. Dissimilar distributions can be compared.

Question 11

CHAPTER 5

11. Last week Sarah had exams in math and Spanish. On the math exam, the mean was m=30 with s= 5, and Sarah had a score of X= 45. On the Spanish exam, the mean was m= 60 with s= 6, and Sarah had a score of X= 65. For which class should Sarah expect the better grade?
    a. Math
    b. Spanish
    c. The grades should be the same because the two exam scores are in the same location.
    d. There is not enough information to determine which is the better grade.

Answer 11

a. Math

Question 12

CHAPTER 5

12. A set of scores has a mean of m= 63 and a standard deviation of s= 8. If these scores are standardized so that the new distribution has m= 50 and s= 10, what new value would be obtained for a score of X= 59 from the original distribution?
    a. The score would still be X= 59.
    b. 45
    c. 46
    d. 55

Answer 12

b. 45

Question 13

CHAPTER 5

13. A distribution with m=35 and s=8 is being standardized so that the new mean and standard deviation will be m=50 and s=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 13

b. X=55

Question 14

CHAPTER 5

14. Using z-scores, a sample with M=37 and s=6 is standardized so that the new mean is M=50 and s= 10. How does an individual’s z-score in the new distribution compare with his/her z-score in the original sample?
    a. New z= old z+13
    b. New z= (10/6)(old z)
    c. New z= old z
    d. Cannot be determined with the information given.

Answer 14

c. New z= old z

Question 15

CHAPTER 5

15. For the past 20 years, the high temperature on April 15 has averaged m=60 degrees with a standard deviation of s=4. Last year, the high temperature was 75 degrees. Based on this information, last year’s temperature on April 15 was
    a. a little above average
    b. far above average
    c. above average, but it is impossible to describe how much above average
    d. There is not enough information to compare last year with the average.

Answer 15

b. far above average

Question 16

CHAPTER 5

16. A score of X=75 is obtained from a population. Which set of population parameters would make X=75 an extreme, unrepresentative score?
    a. m=65 and s=8
    b. m=65 and s=3
    c. m=70 and s=8
    d. m=70 and s=3

Answer 16

b. m=65 and s=3

Question 17

CHAPTER 5

17. Under what circumstances would a score that is 20 points above the mean be considered an extreme score?

a. When the mean is much larger than 20.
b. When the standard deviation is much larger than 20.
c. When the mean is much smaller than 20.
d. When the standard deviation is much smaller than 20.

Answer 17

d. When the standard deviation is much smaller than 20.

Question 18

CHAPTER 6

1. An introductory psychology class with n=44 students has 20 freshmen, 14 sophomores, 2 juniors, and 8 seniors. If one student is randomly selected from this class, what is the probability of getting a sophomore?
   a. 8/24
   b. 20/24
   c. 20/44
   d. 14/44

Answer 18

d. 14/44

Question 19

CHAPTER 6

2. A jar contains 10 Snickers bars and 20 Hershey bars. If one candy bar is se- lected from this jar, what is the probability that it will be a Snickers bar?
   a. 1/30
   b. 1/20
   c. 10/30
   d. 10/20

Answer 19

c. 10/30

Question 20

CHAPTER 6

3. Random sampling requires sampling with replacement. What is the goal of sampling with replacement?
   a. It ensures that every individual has an equal chance of selection.
   b. It ensures that the probabilities stay constant from one selection to the next.
   c. It ensures that the same individual is not selected twice.
   d. All of the other options are goals of sampling with replacement.

Answer 20

b. It ensures that the probabilities stay constant from one selection to the next.

Question 21

CHAPTER 6

4. What is the probability of randomly selecting a z-score greater than z=0.25 from a normal distribution?
   a. 0.5987
   b. 0.4013
   c. -0.5987
   d. -0.4013

Answer 21

b. 0.4013

Question 22

CHAPTER 6

5. In a normal distribution, what z-score value separates the highest 90% of the scores from the rest of the distribution?
   a. z=1.28
   b. z=-1.28
   c. z=0.13
   d. z=-0.13

Answer 22

b. z=-1.28

Question 23

CHAPTER 6

6. In a normal distribution, what z-score value separates the lowest 20% of the distribution from the highest 80%?
   a. z=0.20
   b. z=0.80
   c. z=0.84
   d. z=-0.84

Answer 23

d. z=-0.84

Question 24

CHAPTER 6

7. The population of SAT scores forms a normal distribution with a mean of m= 500 and s= 100. What proportion of the population consists of individuals with SAT scores higher than 400?
   a. 0.1587
   b. 0.8413
   c. 0.3413
   d. -0.1587

Answer 24

b. 0.8413

Question 25

# **CHAPTER 6** 8. A normal distribution has m=100 and s=20. What is the probability of randomly selecting a score of greater than 130 from this distribution? a. p=0.9032 b. p=0.9332 c. p=0.0968 d. p=0.0668

Answer 25

**d. p=0.0668**

Question 26

# **CHAPTER 6** 9. For a normal distribution with m=70 and s=10, what is the minimum score necessary to be in the top 60% of the distribution? a. 67.5 b. 62.5 c. 65.2 d. 68.4

Answer 26

**a. 67.5**

Question 27

# **CHAPTER 6** 10. For a population with a m=500 and s=100, which of the following is the percentile rank of a score of X=550? a. 69.15% b. z=+0.50 c. 38.05% d. z=-0.50

Answer 27

**a. 69.15%**

Question 28

# **CHAPTER 6** 11. For a population with a m=100 and s=10, which of the following is the 20th percentile score? a. X=91.60 b. z=-8.40 c. X=108.40 d. z=-0.84

Answer 28

**a. X=91.60**

Question 29

# **CHAPTER 6** 12. Find the interquartile range for a normal distribution with s=50. a. Cannot be determined without more information. b. 67 c. 13.40 d. 25%

Answer 29

**b. 67**

Question 30

# **CHAPTER 6** 13. Which of the following accurately describes a score of X=57 or larger in a normal distribution with m=40 and s=5? a. It is an extreme, very unlikely score. b. It is higher than average but not extreme or unlikely. c. It is a little above average. d. It is an average, representative score.

Answer 30

**a. It is an extreme, very unlikely score.**

Question 31

# **CHAPTER 6** 14. For a normal distribution with m=60 and s=10, what X values form the boundaries between the middle 95% of the distribution and the extreme 5% in the tails? a. 51.6 and 68.4 b. 47.2 and 72.8 c. 43.5 and 65.5 d. 40.4 and 79.6

Answer 31

**d. 40.4 and 79.6**

Question 32

# **CHAPTER 6** 15. An individual is selected from a normal population with a mean of m=80 with s=20, and a treatment is administered to the individual. After treatment, the individual’s score is found to be X=105. How likely is it that a score this large or larger would be obtained if the treatment has no effect? a. p=0.1056 b. p=0.3944 c. p=0.8944 d. p=1.2500

Answer 32

**a. p=0.1056**

Question 33

# **CHAPTER 7** 1. If all the possible random samples, each with n=9 scores, are selected from a normally distributed population with m=90 and s=20, and the mean is calculated for each sample, then what is the average value for all of the sample means? a. 9 b. 90 c. 9(90) =810 d. Cannot be determined without additional information.

Answer 33

**b. 90**

Question 34

# **CHAPTER 7** 2. All the possible random samples of size n=2 are selected from a population with m=40 and s=10 and the mean is computed for each sample. Then all the possible samples of size n=25 are selected from the same population and the mean is computed for each sample. How will the distribution of sample means for n=2 compare with the distribution for n=25? a. The two distributions will have the same mean and variability. b. The mean and variability for n=25 will both be larger than the mean and variability for n=2. c. The mean and variability for n=25 will both be smaller than the mean and variability for n= 2. d. The variability for n=25 will be smaller than the variability for n=2, but the two distributions will have the same mean.

Answer 34

**d. The variability for n=25 will be smaller than the variability for n=2, but the two distributions will have the same mean.**

Question 35

# **CHAPTER 7** 3. If all the possible random samples of size n=25 are selected from a popula- tion with m= 90 and s= 20 and the mean is computed for each sample, then what shape is expected for the distribution of sample means? a. The sample means tend to form a normal-shaped distribution b. The distribution of sample means will have the same shape as the sample distribution. c. The sample will be distributed evenly across the scale, forming a rectangular-shaped distribution. d. There are thousands of possible samples and it is impossible to predict the shape of the distribution.

Answer 35

**a. The sample means tend to form a normal-shaped distribution**

Question 36

# **CHAPTER 7** 4. If random samples, each with n=4 scores, are selected from a normal population with m=90 and s=20, then what is the expected value of the mean for the distribution of sample means? a. 2.5 b. 5 c. 40 d. 90

Answer 36

**d. 90**

Question 37

# **CHAPTER 7** 5. If random samples, each with n=4 scores, are selected from a normal population with m=80 and s=12, and the mean is calculated for each sample, then how much distance is expected on average between M and m? a. 2 points b. 6 points c. 18 points d. Cannot be determined without additional information.

Answer 37

**b. 6 points**

Question 38

# **CHAPTER 7** 7. A sample of n=4 scores has a standard error of 24. What is the standard deviation of the population from which the sample was obtained? a. 48 b. 24 c. 6 d. 3

Answer 38

**a. 48**

Question 39

# **CHAPTER 7** 8. A sample of n=25 scores is obtained from a population with m=70 and s=20. If the sample mean is M=78, then what is the z-score corresponding to the sample mean? a. z=+0.25 b. z=+0.50 c. z=+1.00 d. z=+2.00

Answer 39

**d. z=+2.00**

Question 40

# **CHAPTER 7** 9. A random sample of n=4 scores is obtained from a normal population with m=20 and s=4. What is the probability of obtaining a mean greater than M=22 for this sample? a. 0.50 b. 1.00 c. 0.1587 d. 0.3085

Answer 40

**c. 0.1587**

Question 41

# **CHAPTER 7** 10. A random sample of n=4 scores is obtained from a normal population with m=40 and s=6. What is the probability of obtaining a mean greater than M=46 for this sample? a. 0.3085 b. 0.1587 c. 0.0668 d. 0.0228

Answer 41

**d. 0.0228**

Question 42

# **CHAPTER 7** 11. Which of the following would cause the standard error of M to get larger? a. Increasing both the sample size and standard deviation. b. Decreasing both the sample size and standard deviation. c. Increasing the sample size and decreasing the standard deviation. d. Decreasing the sample size and increasing the standard deviation.

Answer 42

**d. Decreasing the sample size and increasing the standard deviation.**

Question 44

# **CHAPTER 7** 12. A sample obtained from a population with s=8 has a standard error of 2 points. How many scores are in the sample? a. n=5 b. n=10 c. n=16 d. n=25

Answer 44

**c. n=16**

Question 45

# **CHAPTER 7** 13. A random sample is selected from a population with m=80 and s=20. How large must the sample be to ensure a standard error of 2 points or less? a. n=10 b. n=25 c. n=100 d. It is impossible to obtain a standard error of less than 2 for any sized sample.

Answer 45

**c. n=100**

Question 46

# **CHAPTER 7** 14. A sample is obtained from a population with m=100 and s=20. Which of the following samples would produce the z-score closest to zero? a. A sample of n=25 scores with M=102 b. A sample of n=100 scores with M=102 c. A sample of n=25 scores with M=104 d. A sample of n=100 scores with M=104

Answer 46

**a. A sample of n=25 scores with M=102**

Question 47

# **CHAPTER 7** 15. For a normal population with m=80 and s=20, which of the following samples is least likely to be obtained? a. M=88 for a sample of n=4 b. M=84 for a sample of n=4 c. M=88 for a sample of n=25 d. M=84 for a sample of n=25

Answer 47

**c. M=88 for a sample of n=25**

Question 48

# **CHAPTER 7** 16. For a sample selected from a normal population with m=100 and s=15, which of the following would be the most extreme and unrepresentative? a. M=90 for a sample of n=9 scores b. M=90 for a sample of n=25 scores c. M=95 for a sample of n=9 scores d. M=95 for a sample of n=25 scores

Answer 48

**b. M=90 for a sample of n=25 scores**

Question 49

# **CHAPTER 8** 1. In general terms, what is a hypothesis test? a. A descriptive technique that allows researchers to describe a sample b. A descriptive technique that allows researchers to describe a population c. An inferential technique that uses the data from a sample to draw inferences about a population. d. An inferential technique that uses information about a population to make predictions about a sample.

Answer 49

**c. An inferential technique that uses the data from a sample to draw inferences about a population.**

Question 50

# **CHAPTER 8** 2. A sample is selected from a population with a mean of m=75 and a treatment is administered to the individuals in the sample. If a hypothesis test is used to evaluate the treatment effect, then what is the correct statement of the null hypothesis? a. m=75 b. m ≠ 75 c. M=75 d. M ≠ 75

Answer 50

**a. m=75**

Question 51

# **CHAPTER 8** 3. Which of the following accurately describes the critical region for a hypothesis test? a. Outcomes that have a very low probability if the null hypothesis is true. b. Outcomes that have a high probability if the null hypothesis is true. c. Outcomes that have a very low probability regardless of whether the null hypothesis is true. d. Outcomes that have a high probability regardless of whether the null hy- pothesis is true.

Answer 51

**a. Outcomes that have a very low probability if the null hypothesis is true.**

Question 52

# **CHAPTER 8** 4. The psychology department is gradually changing its curriculum by increasing the number of online course offerings. To evaluate the effectiveness of this change, a random sample of n=36 students who registered for Introductory Psychology is placed in the online version of the course. At the end of the semester, all students take the same final exam. The average score for the sample is M=76. For the general population of students taking the traditional lecture class, the final exam scores form a normal distribution with a mean of m=71 and a standard deviation of s=12. The department conducts a hypothesis test with a=.05. Which of the following correctly describes the outcome of the hypothesis test? a. Reject the null hypothesis because z=+2.50, which is in the critical region. b. Reject the null hypothesis because z=+2.50, which is in the critical region. c. Fail to reject the null hypothesis because z=+0.42, which is not in the critical region. d. Fail to accept the alternative hypothesis because z=+0.42, which is inside of the critical region.

Answer 52

**a. Reject the null hypothesis because z=+2.50, which is in the critical region.**

Question 53

# **CHAPTER 8** 5. What does a Type II error mean? a. A researcher has falsely concluded that a treatment has an effect. b. A researcher has correctly concluded that a treatment has no effect. c. A researcher has falsely concluded that a treatment has no effect. d. A researcher has correctly concluded that a treatment has an effect.

Answer 53

**c. A researcher has falsely concluded that a treatment has no effect.**

Question 54

# **CHAPTER 8** 6. What does a Type I error mean? a. A researcher has concluded that a treatment has an effect when it really does. b. A researcher has concluded that a treatment has no effect when it really does not. c. A researcher has concluded that a treatment has no effect when it really does d. A researcher has concluded that a treatment has an effect when it really does not.

Answer 54

**d. A researcher has concluded that a treatment has an effect when it really does not.**

Question 55

# **CHAPTER 8** 7. What is the consequence of increasing the alpha level (for example, from .01 to .05)? a. It will increase the likelihood of rejecting H0 and increase the risk of a Type I error. b. It will decrease the likelihood of rejecting H0 and increase the risk of a Type I error. c. It will increase the likelihood of rejecting H0 and decrease the risk of a Type I error. d. It will decrease the likelihood of rejecting H0 and decrease the risk of a Type I error.

Answer 55

**a. It will increase the likelihood of rejecting H0 and increase the risk of a Type I error.**

Question 56

# **CHAPTER 8** 8. A research report includes the statement, “z=1.18, p >.05.” What happened in the hypothesis test? a. The obtained sample mean was very unlikely if the null hypothesis is true, so H0 was rejected. b. The obtained sample mean was very likely if the null hypothesis is true, so H0 was rejected. c. The obtained sample mean was very unlikely if the null hypothesis is true, and the test failed to reject H0. d. The obtained sample mean was very likely if the null hypothesis is true, and the test failed to reject H0.

Answer 56

**d. The obtained sample mean was very likely if the null hypothesis is true, and the test failed to reject H0.**

Question 57

# **CHAPTER 8** 9. A researcher uses a hypothesis test to evaluate H0: m=90. Which combination of factors is most likely to result in rejecting the null hypothesis? a. M=95 and s=10 b. M=95 and s=20 c. M=100 and s=10 d. M=100 and s=20

Answer 57

**c. M=100 and s=10**

Question 58

# **CHAPTER 8** 10. What assumptions are required for a z-score hypothesis test? a. The scores are obtained by random sampling. b. The scores in the sample are independent observations. c. The distribution of sample means is normal. d. all of the above

Answer 58

**d. all of the above**

Question 59

# **CHAPTER 8** 11. A population is known to have a mean of m=45. A treatment is expected to increase scores for individuals in this population. If the treatment is evaluated using a one-tailed hypothesis, then which of the following is the correct statement of the null hypothesis? a. m ≥ 45 b. m>45 c. m ≤ 45 d. m<45

Answer 59

**c. m ≤ 45**

Question 60

# **CHAPTER 8** 12. A researcher is conducting an experiment to evaluate a treatment that is expected to decrease the scores for individuals in a population that is known to have a mean of m=95. The results will be examined using a one-tailed hypothesis test. Which of the following is the correct statement of the alterna- tive hypothesis (H1)? a. m > 95 b. m ≥ 95 c. m < 95 d. m ≤ 95

Answer 60

**c. m < 95**

Question 61

# **CHAPTER 8** 13. A researcher expects a treatment to produce an increase in the population mean. Assuming a normal distribution, what is the critical z-score for a one-tailed test with a= .01? a. +2.33 b. ± 2.58 c. +1.65 d. ± 2.33

Answer 61

**a. +2.33**

Question 62

# **CHAPTER 8** 14. Statistical significance tells us what? a. That the treatment effect is substantial. b. About the size of the treatment effect. c. That the results are unlikely to have occurred if there is no treatment effect. d. That the results are likely to have occurred if there is a treatment effect.

Answer 62

**c. That the results are unlikely to have occurred if there is no treatment effect.**

Question 63

# **CHAPTER 8** 15. A sample of n=9 scores is selected from a population with a mean of m=80 and s=12, and a treatment is administered to the sample. After the treatment, the researcher measures effect size with Cohen’s d and obtains d=0.25. What was the sample mean? a. M=81 b. M=82 c. M=83 d. M=84

Answer 63

**c. M=83**

Question 64

# **CHAPTER 8** 16. If other factors are held constant, then how does sample size affect the likelihood of rejecting the null hypothesis and the value for Cohen’s d? a. A larger sample increases the likelihood of rejecting the null hypothesis and increases the value of Cohen’s d. b. A larger sample increases the likelihood of rejecting the null hypothesis but decreases the value of Cohen’s d. c. A larger sample increases the likelihood of rejecting the null hypothesis but has no effect on the value of Cohen’s d. d. A larger sample decreases the likelihood of rejecting the null hypothesis but has no effect on the value of Cohen’s d.

Answer 64

**c. A larger sample increases the likelihood of rejecting the null hypothesis but has no effect on the value of Cohen’s d.**

Question 65

# **CHAPTER 8** 17. Under what circumstances is a very small treatment effect most likely to be statistically significant? a. With a large sample and a large standard deviation. b. With a large sample and a small standard deviation. c. With a small sample and a large standard deviation. d. With a small sample and a small standard deviation.

Answer 65

**b. With a large sample and a small standard deviation.**

Question 66

# **CHAPTER 8** 18. If the power of a hypothesis test is found to be p= 0.80, then what is the probability of a Type II error for the same test? a. p=0.20 b. p=0.80 c. The probability of a Type II error is not related to power. d. It is impossible to determine without knowing the alpha level for the test.

Answer 66

**a. p=0.20**

Question 67

# **CHAPTER 8** 19. Suppose that a researcher is planning a study and would like to esti- mate the study’s power before collecting data. Assuming that the null distribu- tion has a mean of m= 80 and a standard deviation of s=21, what is the power of a= .05, two-tailed, hypothesis test with an expected treatment effect of -20. Sample size is n=9. Notice that Step 1 of this power analysis is depicted in Figure 8.11. a. 0.1841 b. 0.8159 c. 0.3821 d. 0.6179

Answer 67

**b. 0.8159**

Question 68

# **CHAPTER 8** 20. How does the sample size influence the likelihood of rejecting the null hypothesis and the power of the hypothesis test? a. Increasing sample size increases both the likelihood of rejecting H0 and the power of the test. b. Increasing sample size decreases both the likelihood of rejecting H0 and the power of the test. c. Increasing sample size increases the likelihood of rejecting H0, but the power of the test is unchanged. d. Increasing sample size decreases the likelihood of rejecting H0, but the power of the test is unchanged.

Answer 68

**a. Increasing sample size increases both the likelihood of rejecting H0 and the power of the test**

Question 69

# **CHAPTER 8** 21. How is the power of a hypothesis test related to sample size and the alpha level? a. A larger sample and a larger alpha level will both increase power. b. A larger sample and a larger alpha level will both decrease power. c. A larger sample will increase power, but a larger alpha will decrease power. d. A larger sample will decrease power, but a larger alpha will increase power.

Answer 69

**a. A larger sample and a larger alpha level will both increase power.**

Question 70

# **CHAPTER 9** 1. In what circumstances is the t statistic used instead of a z-score for a hypothesis test? a. The t statistic is used when the sample size is n=30 or larger. b. The t statistic is used when the population mean is known. c. The t statistic is used when the population variance (or standard deviation) is unknown. d. The t statistic is used if you are not sure that the population distribution is normal.

Answer 70

**c. The t statistic is used when the population variance (or standard deviation) is unknown.**

Question 71

# **CHAPTER 9** 2. A sample of n=9 scores has SS=72. What is the estimated standard error for the sample mean? a. 9 b. 3 c. 1 d. 2

Answer 71

**c. 1**

Question 72

# **CHAPTER 9** 3. On average, what value is expected for the t statistic when the null hypothesis is true? a. 0 b. 1 c. 1.96 d. t > 1.96

Answer 72

**a. 0**

Question 73

# **CHAPTER 9** 4. A sample of n=25 scores is selected from a population with a mean of m=73, and a treatment is administered to the sample. After treatment, the sample has M=70 and s^2=100. If a hypothesis test with a t statistic is used to evaluate the treatment effect, then what value will be obtained for the t statistic? a. t=-0.75 b. t=-3.00 c. t=-1.50 d. t=+1.50

Answer 73

**c. t=-1.50**

Question 74

# **CHAPTER 9** 5. A hypothesis test produces a t statistic of t= 2.30. If the researcher is using a two-tailed test with a=.05, how large does the sample have to be in order to reject the null hypothesis? a. At least n=8 b. At least n=9 c. At least n=10 d. At least n=11

Answer 74

**c. At least n=10**

Question 75

# **CHAPTER 9** 6. A sample is selected from a population and a treatment is administered to the sample. For a hypothesis test with a t statistic, if there is a 5-point difference between the sample mean and the original population mean, which set of sample characteristics is most likely to lead to a decision that there is a significant treatment effect? a. Small variance for a large sample. b. Small variance for a small sample. c. Large variance for a large sample. d. Large variance for a small sample.

Answer 75

**a. Small variance for a large sample.**

Question 76

# **CHAPTER 9** 7. A sample of n=25 is selected from a population with m=40, and a treatment is administered to each individual in the sample. After treatment, the sample mean is M=44 with a sample variance of s^2=100. Based on this information, what is the size of the treatment effect as measured by Cohen’s d? a. d=0.04 b. d=0.40 c. d=1.00 d. d=2.00

Answer 76

**b. d=0.40**

Question 77

# **CHAPTER 9** 8. A sample is selected from a population with a mean of m= 75, and a treatment is administered to the individuals in the sample. The researcher intends to use a t sta- tistic to evaluate the effect of the treatment. If the sample mean is M= 79, then which of the following outcomes would produce the largest value for Cohen’s d? a. n= 4 and s^2= 30 b. n= 16 and s^2= 30 c. n=25 and s^2=30 d. All three samples would produce the same value for Cohen’s d.

Answer 77

**d. All three samples would produce the same value for Cohen’s d.**

Question 78

# **CHAPTER 9** 9. A sample of n=4 scores is selected from a population with an unknown mean. The sample has a mean of M=40 and a variance of s^2=16. Which of the following is the correct 90% confidence interval for m? a. m=40 ± 2.353(4) b. m=40 ± 1.638(4) c. m=40 ± 2.353(2) d. m=40 ± 1.638(2)

Answer 78

**c. m=40 ± 2.353(2)**

Question 79

# **CHAPTER 9** 10. A researcher uses a sample of n=25 individuals to evaluate the effect of a treatment. The hypothesis test uses a= .05 and produces a significant result with t=2.15. How would this result be reported in the literature? a. t(25)=2.15,p<.05 b. t(24)=2.15,p<.05 c. t(25)=2.15,p>.05 d. t(24)=2.15,p>.05

Answer 79

**b. t(24)=2.15,p<.05**

Question 80

# **CHAPTER 9** 11. A sample is selected from a population with a mean of m= 50, and a treatment is administered to the sample. If the treatment is expected to increase scores and a t statistic is used for a one-tailed hypothesis test, then which of the following is the correct null hypothesis? a. m ≤50 b. m<50 c. m≥ 50 d. m>50

Answer 80

**a. m ≤50**

Question 81

# **CHAPTER 9** 12. A researcher predicts that a treatment will increase scores. To test the treat- ment effect, a sample of n= 16 is selected from a population with m= 80 and a treatment is administered to the individuals in the sample. After treatment, the sample mean is M= 78 with s^2= 16. If the researcher uses a one-tailed test with a= .05, then what decision should be made? a. Reject H0 with a= .05 or with a= .01 b. Fail to reject H0 with a= .05 or with a=.01 c. Reject H0 with a= .05 but not with a= .01 d. Reject H0 with a= .01 but not with a= .05

Answer 81

**b. Fail to reject H0 with a= .05 or with a=.01**

Question 82

# **CHAPTER 9** 13. A researcher fails to reject the null hypothesis with a regular two-tailed test using a= .05. If instead the researcher had used a directional (one-tailed) test with the same data and the same alpha level, then what decision would be made? a. Definitely reject the null hypothesis. b. Definitely reject the null hypothesis if the treatment effect is in the predicted direction. c. Definitely fail to reject the null hypothesis. d. Possibly reject the null hypothesis if the treatment effect is in the predicted direction.

Answer 82

**d. Possibly reject the null hypothesis if the treatment effect is in the predicted direction.**

Question 83

# **CHAPTER 10** 1. Which of the following is most likely to be an independent-measures design? a. A study comparing vocabulary size of 3-year-old children from lower socioeconomic status homes and 3-year-old children from higher socioeconomic status homes. b. A study comparing classroom learning with and without background music. c. A study comparing blood pressure before and after a workout. d. A study evaluating jet lag by comparing cognitive performance at the beginning and end of a cross-country flight.

Answer 83

**a. A study comparing vocabulary size of 3-year-old children from lower socioeconomic status homes and 3-year-old children from higher socioeconomic status homes.**

Question 84

# **CHAPTER 10** 2. Which of the following is most likely to be a repeated-measures design? a. A study comparing artistic skills performance for left-handed adolescents and right-handed adolescents. b. A study comparing cholesterol levels before and after a diet featuring oatmeal. c. A study comparing self-esteem for 6-year-old boys and 6-year-old girls. d. A study comparing Facebook use for adolescents and over-30 adults.

Answer 84

**b. A study comparing cholesterol levels before and after a diet featuring oatmeal.**

Question 85

# **CHAPTER 10** 3. An independent-measures study comparing two treatment conditions uses _____________ groups of participants and obtains _____________ score(s) for each participant. a. 1, 1 b. 1, 2 c. 2, 1 d. 2, 2

Answer 85

**c. 2, 1**

Question 86

# **CHAPTER 10** 4. Which of the following is the correct null hypothesis for an independent-measures t test? a. There is no difference between the two sample means. b. There is no difference between the two population means. c. The difference between the two sample means is identical to the difference between the two population means. d. None of the other three choices is correct.

Answer 86

**b. There is no difference between the two population means.**

Question 87

# **CHAPTER 10** 5. Which of the following does not accurately describe the relationship between the formulas for the single-sample t and the independent-measures t? a. The single-sample t has one sample mean and the independent-measures t has two. b. The single-sample t has one population mean and the independent-measures t has two. c. The single-sample t uses one sample variance to compute the standard error and the independent-measures t uses two. d. All of the above accurately describe the relationship.

Answer 87

**d. All of the above accurately describe the relationship.**

Question 88

# **CHAPTER 10** 6. One sample has n=21 and a second sample has n=35. If the pooled variance for the two samples is 210, then what is the estimated standard error for the sample mean difference? a. 9 b. 4 c. 3 d. 2

Answer 88

**b. 4**

Question 89

# **CHAPTER 10** 7. A researcher obtains M=34 with SS=190 for a sample of n=10 girls, and M=29 with SS=170 for a sample of n=10 boys. If the two samples are used to evaluate the mean difference between the two populations, what value will be obtained for the t statistic? a. 5/4= 1.25 b. 5/2= 2.50 c. 5/√ 2= 3.54 d. 5/1= 5.00

Answer 89

**b. 5/2= 2.50**

Question 90

# **CHAPTER 10** 8. What is the value of the independent-measures t statistic for a study with n=10 participants in each treatment if the data produce M=38 and SS=200 for the first treatment, and M= 33 and SS= 160 for the second treatment? a. t =1.25 b. t=2.50 c. t =0.25 d. t = 5√20= 1.12

Answer 90

**b. t=2.50**

Question 91

# **CHAPTER 10** 9. A researcher uses two samples, each with n=15 participants, to evaluate the mean difference in performance scores between 8-year-old and 10-year-old children. The prediction is that the older children will have higher scores. The sample mean for the older children is five points higher than the mean for the younger children and the pooled variance for the two samples is 30. For a onetailed test, what decision should be made? a. Reject the null hypothesis with a= .05 but not with a=.01. b. Reject the null hypothesis with either a= .05 or a= .01. c. Fail to reject the null hypothesis with a= .05 but not with a= .01. d. Fail to reject the null hypothesis with either a= .05 or a= .01.

Answer 91

**b. Reject the null hypothesis with either a= .05 or a= .01.**

Question 92

# **CHAPTER 10** 10. Hartley’s F-max test is used to evaluate the homogeneity of variance assumption. What is the null hypothesis for this test? a. The two sample variances are equal. b. The two sample variances are not equal. c. The two population variances are equal. d. The two population variances are not equal.

Answer 92

**c. The two population variances are equal.**

Question 93

# **CHAPTER 10** 11. A researcher obtains a mean of M=26 for a sample in one treatment condition and M= 28 for a sample in another treatment. The pooled variance for the two samples is 16. What value would be obtained if Cohen’s d were used to measure the effect size? a. 2/16 b. 4/16 c. 2/4 d. There is not enough information to determine Cohen’s d.

Answer 93

**c. 2/4**

Question 94

# **CHAPTER 10** 12. Which of the following is not an accurate description of a confidence interval for a mean difference using the independent-measures t statistic? a. The sample mean difference, M1- M2, will be located in the center of the interval. b. If other factors are held constant, the width of the interval will decrease if the sample size is increased. c. If other factors are held constant, the width of the interval will increase if the percentage of confidence is increased. d. If other factors are held constant, the width of the interval will increase if the difference between the two sample means is increased.

Answer 94

**d. If other factors are held constant, the width of the interval will increase if the difference between the two sample means is increased.**

Question 95

# **CHAPTER 10** 13. Which of the following accurately describes the 95% confidence interval for an independent-measures study for which a hypothesis test concludes that there is no significant mean difference with a= .05? a. The confidence interval will include the value 0. b. The confidence interval will not include the value 0. c. The confidence interval will not include the value M1- M2. d. None of the other options is accurate

Answer 95

**a. The confidence interval will include the value 0.**

Question 96

# **CHAPTER 10** 14. The results of a hypothesis test with an independent-measures t statistic are reported as follows: t(22)= 2.48, p< .05, d= 0.27. Which of the following is an accurate description of the study and the result? a. The study used a total of 24 participants and the null hypothesis was rejected. b. The study used a total of 22 participants and the null hypothesis was rejected. c. The study used a total of 24 participants and the null hypothesis was not rejected. d. The study used a total of 22 participants and the null hypothesis was not rejected.

Answer 96

**a. The study used a total of 24 participants and the null hypothesis was rejected.**

Question 97

# **CHAPTER 10** 15. Which of the following accurately describes how the outcome of a hypothesis test and measures of effect size with the independent-measures t statistic are affected when sample size is increased? a. The likelihood of rejecting the null hypothesis and measures of effect size both increase. b. The likelihood of rejecting the null hypothesis and measures of effect size both decrease. c. The likelihood of rejecting the null hypothesis increases and there is little or no effect on measures of effect size. d. The likelihood of rejecting the null hypothesis decreases and there is little or no effect on measures of effect size.

Answer 97

**c. The likelihood of rejecting the null hypothesis increases and there is little or no effect on measures of effect size.**

Question 98

# **CHAPTER 10** 16. Which of the following accurately describes how the outcome of a hypothesis test and measures of effect size with the independent-measures t statistic are affected when sample variance increases? a. The likelihood of rejecting the null hypothesis and measures of effect size both increase. b. The likelihood of rejecting the null hypothesis and measures of effect size both decrease. c. The likelihood of rejecting the null hypothesis increases and there is little or no effect on measures of effect size. d. The likelihood of rejecting the null hypothesis decreases and there is little or no effect on measures of effect size.

Answer 98

**b. The likelihood of rejecting the null hypothesis and measures of effect size both decrease.**

Question 99

# **CHAPTER 10** 17. Which of the following sets of data would produce the largest value for an independent-measures t statistic? a. Two sample means of 10 and 12 with sample variances of 20 and 25. b. Two sample means of 10 and 12 with variances of 120 and 125. c. Two sample means of 10 and 20 with variances of 20 and 25. d. Two sample means of 10 and 20 with variances of 120 and 125.

Answer 99

**c. Two sample means of 10 and 20 with variances of 20 and 25.**

Question 100

# **CHAPTER 11** 1. In a repeated-measures study, the same group of individuals participates in all of the treatment conditions. Which of the following situations is not an example of a repeated-measures design? a. A researcher would like to study the effect of practice on performance in the same sample of participants. b. A researcher would like to compare individuals from two different populations. c. The effect of a treatment is studied in a small group of individuals with a rare disease by measuring their symptoms before and after treatment. d. A developmental psychologist examines how behavior unfolds by observing the same group of children at different ages.

Answer 100

**b. A researcher would like to compare individuals from two different populations.**

Question 101

# **CHAPTER 11** 2. A researcher conducts a research study comparing two treatment conditions and obtains 10 scores in each treatment. If the researcher used a repeatedmeasures design, then how many subjects participated in the research study? a. 10 b. 20 c. 21 d. 40

Answer 101

**a. 10**

Question 102

# **CHAPTER 11** 3. . For an experiment comparing two treatment conditions, an independentmeasures design would obtain ____ score(s) for each subject and a repeatedmeasures design would obtain ____ score(s) for each subject. a. 1, 1 b. 1, 2 c. 2, 1 d. 2, 2

Answer 102

**b. 1, 2**

Question 103

# **CHAPTER 11** 4. What is the mean for the difference scores for the following data from a repeated-measures study? a. 16 b. 6 c. 8 d. 44 I II 5 13 2 10 6 6 7 15

Answer 103

**b. 6**

Question 104

# **CHAPTER 11** 5. Which of the following is the correct statement of the null hypothesis for a repeated-measures hypothesis test? a. MD=0 b. mD=0 c. m1=m2 d. M1=M2

Answer 104

**b. mD=0**

Question 105

# **CHAPTER 11** 6. Which of the following accurately describes the relationship between the repeated-measures t statistic and the single-sample t statistic? a. Each uses one sample mean. b. Each uses one population mean. c. Each uses one sample variance to compute the standard error. d. All of the above.

Answer 105

**d. All of the above.**

Question 106

# **CHAPTER 11** 7. What is the value for the estimated standard error for a set of n=11 difference scores with SS=990? a. 40 b. 3 c. 2 d. 1

Answer 106

**b. 3**

Question 107

# **CHAPTER 11** 8. A researcher conducts a repeated-measures study comparing two treatment conditions with a sample of n= 8 participants and obtains a t statistic of t=2.381. Which of the following is the correct decision for a two-tailed test? a. Reject the null hypothesis with a= .05 but fail to reject with a= .01 b. Reject the null hypothesis with either a= .05 or a= .01 c. Fail to reject the null hypothesis with either a=.05 or a= .01 d. Cannot determine the correct decision without more information

Answer 107

**a. Reject the null hypothesis with a= .05 but fail to reject with a= .01**

Question 108

# **CHAPTER 11** 9. A researcher is using a one-tailed hypothesis test to evaluate the significance of a mean difference between two treatments in a repeated-measures study. If the treatment is expected to increase scores, then which of the following is the correct statement of the alternative hypothesis (H1)? a. uD≥0 b. uD ≤ 0 c. uD>0 d. uD< 0

Answer 108

**c. uD>0**

Question 109

# **CHAPTER 11** 10. The results of a repeated-measures study with n=5 participants produce a mean difference of MD=20 points with SS=500 for the difference scores and a t statistic of t=4.00. If the percentage of variance, r^2 , is used to measure effect size, then what is the value of r^2? a. 16/20= 0.8 b. 4/20 =0.2 c. 4/8=0.5 d. 16/8= 2.0

Answer 109

**a. 16/20= 0.8**

Question 110

# **CHAPTER 11** 11. For a repeated-measures study with n=16 scores in each treatment, a researcher constructs an 95% confidence interval to describe the mean difference between treatments. What value is at the center of the interval and what t values are used to construct the interval? a. The sample mean difference is at the center and t=±2.131. b. The sample mean difference is at the center and t=±1.753. c. Zero is at the center and t=±2.131. d. Zero is at the center and t=±1.753.

Answer 110

**a. The sample mean difference is at the center and t=±2.131.**

Question 111

# **CHAPTER 11** 12. . A research report describing the results from a repeated-measures study states, “The data showed a significant difference between treatments, t(22)=4.71, p< .01. ”From this report, what can you conclude about the outcome of the hypothesis test? a. The test rejected the null hypothesis. b. The test failed to reject the null hypothesis. c. The test resulted in a Type I error. d. The test resulted in a Type II error.

Answer 111

**a. The test rejected the null hypothesis.**

Question 112

# **CHAPTER 11** 13. A repeated-measures study finds a mean difference of MD=5 points between two treatment conditions. Which of the following sample characteristics is most likely to produce a significant t statistic for the hypothesis test? a. A large sample size (n) and a large variance. b. A large sample size (n) and a small variance. c. A small sample size (n) and a large variance. d. A small sample size (n) and a small variance.

Answer 112

**b. A large sample size (n) and a small variance.**

Question 113

# **CHAPTER 11** 14. If the results of a repeated-measures study show that nearly all of the participants score around 5 points higher in Treatment A than in Treatment B, then which of the following accurately describes the data? a. The variance of the difference scores is small and the likelihood of a significant result is low. b. The variance of the difference scores is small and the likelihood of a significant result is high. c. The variance of the difference scores is large and the likelihood of a significant result is low. d. The variance of the difference scores is large and the likelihood of a significant result is high.

Answer 113

**b. The variance of the difference scores is small and the likelihood of a significant result is high.**

Question 114

# **CHAPTER 11** 15. Which of the following possibilities is a concern with a repeated-measures study? a. Negative values for the difference scores. b. Carryover effects. c. Obtaining a mean difference that is due to individual differences rather than treatment differences. d. All of the other options are major concerns.

Answer 114

**b. Carryover effects.**

Question 115

# **CHAPTER 11** 16. For which of the following situations would an independent-measures design have the maximum advantage over a repeated-measures design? a. When individual differences are small and participating in one treatment is likely to produce a permanent change in the participant’s performance. b. When individual differences are small and participating in one treatment is not likely to produce a permanent change in the participant’s performance. c. When individual differences are large and participating in one treatment is likely to produce a permanent change in the participant’s performance. d. When individual differences are large and participating in one treatment is not likely to produce a permanent change in the participant’s performance.

Answer 115

**a. When individual differences are small and participating in one treatment is likely to produce a permanent change in the participant’s performance.**

Question 116

# **CHAPTER 11** 17. A matched-subjects study comparing two treatments with 10 scores in each treatment requires a total of ____________ participants and measures ____ score(s) for each individual. a. 10, 1 b. 10, 2 c. 20, 1 d. 20, 2

Answer 116

**c. 20, 1**