PSY-K 300 FINAL
A survey records the number of cars owned per household. The number of cars is a: A.) Discrete variable measured on a ratio scale B.) Discrete variable measured on an interval scale C.) Continuous variable measured on a ratio scale D.) Continuous variable measured on an ordinal scale
A
For any distribution, what is the z-score corresponding to the mean? A. 0 B. Z C. 1 D. N
A. 0
What is the value of SS (sum of squared deviations) for the following population? Population: 1, 1, 1, 5 A. 12 B. 28 C. 7 D. 3
A. 12
A normal distribution has a mean of µ = 40 with σ = 10. What proportion of the scores in this distribution are greater than X = 55? A. 0.0668 B. 0.3085 C. 0.9332 D. 0.6915
A. 0.0668
A population has a mean of µ = 30. If 3 points are added to each score, what is the mean for the new distribution? A. 33 B. 30 C. 27 D. 3
A. 33
Samples of size n = 9 are selected from a population with μ = 80 with σ = 18. What is the expected value of M, the mean of the distribution of sample means? A. 80 B. 18 C. 80/3 D. 6
A. 80
What is the consequence of a Type I error? A. Concluding that a treatment has an effect when it really has no effect B. Concluding that a treatment has an effect when it really does C. Concluding that a treatment has no effect when it really does D. Concluding that a treatment has no effect when it really has no effect
A. Concluding that a treatment has an effect when it really has no effect
For an exam with a mean of M = 74 and a standard deviation of s = 8, Mary has a score of X = 80, Bob's score corresponds to z = +1.50, and Sue's score is located above the mean by 10 points. If the students are placed in order from smallest score to largest score, what is the correct order? A. Mary, Sue, Bob B. Sue, Bob, Mary C. Bob, Mary, Sue D. Mary, Bob, Sue
A. Mary, Sue, Bob
Last week, Sarah had exams in Math, Spanish, and English. On the Math exam, the mean was µ = 30 with s = 5, and Sarah had a score of X = 45. On the Spanish exam, the mean was µ = 60 with s = 8 and Sarah had a score of X = 68. On the English exam, the mean was µ = 70 with s = 8 and Sarah had a score of X = 70. For which class should Sara expect the better grade? A. Math B. Grades are the same. C. English D. Spanish
A. Math
Which of the following represents the probability of a Type II error? A. β B. σ C. µ D. α
A. β
Although a research study is typically conducted with a relatively small group of participants known as a ____, most researchers hope to generalize their results to a much larger group known as a ____. A.) Sample; population B.) Statistic; sample C.) Population; sample D.) Parameter; population
A.) Sample, population
A researcher conducts an experiment to determine whether moderate doses of St. John's wort have any effect on memory for college students. For this study, what is the independent variable? A.) The amount of St. John's wort given to each participant B.) The memory score for each participant C.) The group of college students D.) Whether or not they are full-time students
A.) The amount of St. John's wort given to each participant
A hypothesis test produces a t statistic of t = 2.20. If the researcher is using a two-tailed test with α = .05, how large does the sample have to be in order to reject the null hypothesis? A.At least n = 13 B. At least n = 12 C. At least n = 11 D. At least n = 14
A.At least n = 13
On average, what value is expected for the t statistic when the null hypothesis is true? A. t > 1.96 B. 0 C. 1.96 D. 1
B. 0
A sample of n = 4 scores has ΣX = 8 and ΣX2 = 40. What is the value of the sample variance, s2? A. 2 B. 8 C. 10 D. 4
B. 8
What proportion of a normal distribution is located in the tail beyond z = +2.00? A. 0.4772 B. 0.0228 C. 0.0456 D. 0.9772
B. 0.0228
What proportion of a normal distribution is located in the tail beyond z = -1.00? A. -0.3413 B. 0.1587 C. -0.1587 D. 0.8413
B. 0.1587
John drives to work each morning and the trip takes an average of µ = 38 minutes. The distribution of driving times is approximately normal with a standard deviation of σ = 5 minutes. For a randomly selected morning, what is the probability that John's drive to work will take less than 35 minutes? A. 0.6554 B. 0.2743 C. 0.7257 D. 0.3446
B. 0.2743
If a hypothesis test is found to have power = 0.70, then what is the probability that the test will result in a Type II error? A. 0.70 B. 0.30 C. 0.40 D. p > 0.70
B. 0.30
Which set of scores has the smallest standard deviation? A. 27, 105, 10, 80 B. 145, 143, 145, 147 C. 11, 17, 31, 53 D. 5, 11, 42, 22
B. 145, 143, 145, 147
For a binomial distribution with p = q = 1/2 and n = 36, what is the mean for the normal approximation? A. 16 B. 18 C. 3 D. 9
B. 18
Which set of characteristics will produce the smallest value for the estimated standard error? A. A large sample size and a large sample variance B. A large sample size and a small sample variance C. A small sample size and a small sample variance D. A small sample size and a large sample variance
B. A large sample size and a small sample variance
Which of the following will increase the power of a statistical test? A. Change α from .05 to .01 B. Change the sample size from n = 25 to n = 100 C. None of the other three options will increase the power. D. Change from a one-tailed test to a two-tailed test
B. Change the sample size from n = 25 to n = 100
The critical boundaries for a hypothesis test are z = +1.96 and 1.96. If the z-score for the sample data is z = 1.90, then what is the correct statistical decision? A. Reject H0 B. Fail to reject H0 C. Reject H1 D. Fail to reject H1
B. Fail to reject H0
Decreasing the alpha level from α = .05 to α = .01 ____. A. increases the probability that the sample will fall into the critical region B. decreases the probability of a Type I error C. increases the probability of a Type I error D. increases the size of the critical region
B. decreases the probability of a Type I error
If other factors are held constant, which set of sample characteristics is most likely to produce a significant t statistic? A. n = 100 with s2 = 400 B. n = 100 with s2 = 100 C. n = 25 with s2 = 100 D. n = 25 with s2 = 400
B. n = 100 with s2 = 100
Under what circumstances does the binomial distribution approximate a normal distribution? A. when qn > 10 B. when pn and qn are both > 10 C. when pn > 10 D. when npq > 10
B. when pn and qn are both > 10
If a sample of n = 4 scores is obtained from a population with μ = 70 and σ = 12, then what is the z-score corresponding to a sample mean of M = 76? A. z = 0.50 B. z = 1.00 C. z = 2.00 D. z = 0.25
B. z = 1.00
For the following frequency distribution of exam scores, how many students had scores lower than X = 80? X f 90-94 3 85-89 4 80-84 5 75-79 2 70-74 1 A.) 2 B.) 3 C.) 7 D.) 8
B.) 3
What is the mean for the following sample of scores? Scores: 1, 4, 5, 10 A.) 4 B.) 5 C.) 10 D.) 20
B.) 5
A population has µ = 50 and σ = 5. If 10 points are added to every score in the population, then what are the new values for the mean and standard deviation? A. µ = 50 and σ = 5 B. µ = 60 and σ = 15 C. µ = 60 and σ = 5 D. µ = 50 and σ = 15
C. µ = 60 and σ = 5
A random sample of n = 4 scores is obtained from a normal population with µ = 20 and σ = 4. What is the probability that the sample mean will be greater than M = 22? A. 0.3085 B. 0.50 C. 0.1587 A. 1.00
C. 0.1587
What proportion of a normal distribution is located between the mean and z = 1.40? A. 0.8384 B. 0.9192 C. 0.4192 D. 0.0808
C. 0.4192
A sample of n = 16 individuals is selected from a population with μ = 60 and σ = 6 and a treatment is administered to the sample. After treatment, the sample mean is M = 63. What is the value of Cohen's d for this sample? A. 0.33 B. 3.00 C. 0.50 D. 2.00
C. 0.50
A jar contains 10 red marbles and 30 blue marbles. What is the probability of randomly selecting a red marble from the jar? A. 10/30 B. 1/40 C. 10/40 D. 1/10
C. 10/40
The results of a hypothesis test are reported as follows: t(15) = 2.70, p < .05. Based on this report, how many individuals were in the sample? A. 17 B. 15 C. 16 D. 14
C. 16
What is the value of the median for the following set of scores? Scores: 1, 3, 4, 6, 7, 8, 12, 23 A. 7 B. 6 C. 6.5 D. 8
C. 6.5
Which of the following actions will always change the value of the mean? A. Adding a score equal to the mean. B. Removing a score from the distribution C. Changing the value of one score D. Adding a new score to the distribution
C. Changing the value of one score
Even if a treatment has an effect, it is still possible to obtain a sample mean that is very similar to the original population mean. What outcome is likely if this happens? A. Correctly reject H0. B. Correctly fail to reject H0. C. Fail to reject H0 and make a Type II error. D. Reject H0 and make a Type I error.
C. Fail to reject H0 and make a Type II error.
When n is small (less than 30), how does the shape of the t distribution compare to the normal distribution? A. It is taller and narrower than the normal distribution. B. There is no consistent relationship between the t distribution and the normal distribution. C. It is flatter and more spread out than the normal distribution. D. It is almost perfectly normal.
C. It is flatter and more spread out than the normal distribution.
Which of the following is an accurate definition of a Type I error? A. Failing to reject a true null hypothesis B. Rejecting a false null hypothesis C. Rejecting a true null hypothesis D. Failing to reject a false null hypothesis
C. Rejecting a true null hypothesis
With α = .05 and df = 8, the critical values for a two-tailed t test are t = ±2.306. Assuming all other factors are held constant, if the df value were increased to df = 20, what would happen to the critical values for t? A. They would increase (move farther from zero). B. They would stay the same. C. They would decrease (move closer to zero). D. There is not enough information to answer.
C. They would decrease (move closer to zero).
A researcher conducts a hypothesis test using a sample from an unknown population. If the t statistic has df = 35, how many individuals were in the sample? A. n = 35 B. n=32 C. n = 36 D. n = 34
C. n = 36
For a normal population with a mean of µ = 80 and a standard deviation of σ = 10, what is the probability of obtaining a sample mean greater than M = 75 for a sample of n = 25 scores? A. p = 0.3085 B. p = 0.0062 C. p = 0.9938 D. p = 0.6915
C. p = 0.9938
If sample variance is computed by dividing SS by n, then the average value of the sample variances from all the possible random samples will be ____ the population variance. A. exactly equal to B. unrelated to C. smaller than D. larger than
C. smaller than
Which of the following z-score values represents the location closest to the mean? A. z = -1.00 B. z = +1.00 C. z = +0.50 D. z = -2.00
C. z = +0.50
What symbol is used to identify the standard error of M? A. MM B. µ C. σM D. σ
C. σM
Which description provides an example of a continuous variable? A.) The gender of each student in a psychology class B.) The number of males in each class offered by the college C.) The amount of time to solve a problem D.) The number of children in a family
C.) The amount of time to solve a problem
If an entire population with μ = 60 and s = 8 is transformed into z-scores, then the distribution of z-scores will have a mean of ____ and a standard deviation of ____. A. 60 and 8 (unchanged) B. 0 and 8 C. 60 and 1 D. 0 and 1
D. 0 and 1
For a sample of n = 16 scores, how many scores are used to calculate the sample variance? A. 2 B. 8 C. 15 D. 16
D. 16
The sum of the squared deviation scores is SS = 20 for a sample of n = 5 scores. What is the variance for this sample? A. 80 B. 4 C. 100 D. 5
D. 5
For a population with µ = 80 and σ = 10, what is the z-score corresponding to X = 95? A. +0.75 B. +0.50 C. +0.25 D. +1.50
D. +1.50
A normal distribution has a mean of µ = 70 with σ = 12. If one score is randomly selected from this distribution, what is the probability that the score will be greater than X = 79? A. 0.3085 B. 0.2734 C. 0.7734 D. 0.2266
D. 0.2266
What proportion of a normal distribution is located between z = -1.50 and z = +1.50? A. 0.9332 B. 0.0668 C. 0.4332 D. 0.8664
D. 0.8664
For a population with µ = 80 and σ = 20, the distribution of sample means based on n = 16 will have an expected value of ____ and a standard error of ____. A. 5; 80 B. 80; 1.25 C. 20; 20 D. 80; 5
D. 80; 5
What position in the distribution corresponds to a z-score of z = +2.00? A. Below the mean by a distance equal to 2 standard deviations B. Below the mean by 2 points C. Above the mean by 2 points D. Above the mean by a distance equal to 2 standard deviations
D. Above the mean by a distance equal to 2 standard deviations
What is the consequence of a Type II error? A. Concluding that a treatment has an effect when it really does B. Concluding that a treatment has an effect when it really has no effect C. Concluding that a treatment has no effect when it really has no effect D. Concluding that a treatment has no effect when it really does
D. Concluding that a treatment has no effect when it really does
Which of the following accurately describes the critical region? A. Outcomes with a high probability whether or not the null hypothesis is true B. Outcomes with a very low probability whether or not the null hypothesis is true C. Outcomes with a high probability if the null hypothesis is true D. Outcomes with a very low probability if the null hypothesis is true
D. Outcomes with a very low probability if the null hypothesis is true
A researcher measures eye color for a sample of n = 50 people. Which measure of central tendency would be appropriate to summarize the measurements? A. weighted mean B. mean C. median D. mode
D. mode
On an exam with μ = 52, you have a score of X = 56. Which of the following values for the standard deviation would give you the highest position in the class distribution? A. σ = 10 B. σ = 8 C. σ = 4 D. σ = 2
D. σ = 2
A population of N = 6 scores has ΣX = 30. What is the population mean? A.) 30 B.) 15 C.) 180 D.) 5
D.) 5
A researcher uses an anonymous survey to investigate the study habits of American college students. Based on the set of 56 surveys that were completed and returned, the researcher finds that these students spend an average of 4.1 hours each week working on course material outside of class. For this study, the set of 56 students who returned surveys is an example of a ____. A.) Parameter B.) Statistic C.) Population D.) Sample
D.) Sample
Determining a person's reaction time (in milliseconds) would involve measurement on a(n) ____ scale of measurement. A.) nominal B.) ordinal C.) interval D.) ratio
D.) ratio
A sample of n = 4 scores is selected from a population with µ = 70 and s = 10. The probability of obtaining a sample mean greater than 65 is p = 0.8413. (T/F)
FALSE
As the sample size increases, the standard error also increases. (T/F)
FALSE
The binomial distribution for p = 1/2 and n = 100 has a standard deviation of σ = 25. (T/F)
FALSE
A recent report concluded that subjects given a diet containing oat bran had lower cholesterol levels than subjects on a similar diet without oat bran. For this study, cholesterol level is the independent variable. (T/F)
False
The participants in a research study are classified as high, medium, or low in self-esteem. This classification involves measurement on a nominal scale. (T/F)
False
The scores for a very easy exam would probably form a positively skewed distribution. (T/F)
False
There is a total of n = 5 scores in the distribution shown in the following table. X f 5 2 4 8 3 5 2 3 1 2 T/F
False
A directional hypothesis test is also referred to as a one-tailed test. (T/F)
TRUE
A distribution of scores has a mean of 50, a median of 53, and a mode of 56. Based on this information it appears that the distribution is negatively skewed. (T/F)
TRUE
Any individual with a positive z-score has a score greater than the mean. (T/F)
TRUE
Changing the value of a score in a distribution will always change the value of the mean. (T/F)
TRUE
For a population with a mean of µ = 80 and σ = 10, only 2.28% of the scores are greater than X = 100. (T/F)
TRUE
For a population, a deviation score is computed as X - μ. (T/F)
TRUE
For a set of scores measured on an ordinal scale, the median is the preferred measure of central tendency. (T/F)
TRUE
For any normal distribution, the proportion in the tail above z = 2.00 is p = 0.0228. (T/F)
TRUE
If the research prediction is that the treatment will decrease scores, then the critical region for a directional test will be in the left-hand tail. (T/F)
TRUE
If two individuals in the same population have identical X scores, they also will have identical z-scores. (T/F)
TRUE
In a research report, the notation p < .05 indicates that the probability of a Type I error is less than .05. (T/F)
TRUE
The critical region for a hypothesis test consists of sample outcomes that are very unlikely to occur if the null hypothesis is true. (T/F)
TRUE
The distribution of sample means is the collection of sample means for all the possible random samples of a particular size (n) that can be obtained from a population. (T/F)
TRUE
The null hypothesis is stated in terms of the population, even though the data come from a sample. (T/F)
TRUE
The range is usually considered to be a relatively crude measure of variability. (T/F)
TRUE
The sampling error is the natural discrepancy, or amount of error, between a sample statistic and its corresponding population parameter. (T/F)
TRUE
To calculate the variance for a sample, SS is divided by df = n - 1. (T/F)
TRUE
When the population variance or standard deviation is not known, you must use a t statistic instead of a z-score for a hypothesis test. (T/F)
TRUE
A grouped frequency distribution table does not provide enough information to obtain a complete listing of the original set of scores. (T/F)
True
A researcher surveys a sample of n = 200 college students and asks each person to identify his or her favorite movie from the past year. If the results are presented in a frequency distribution graph, the researcher should use a bar graph. (T/F)
True
If a researcher measures two individuals on a nominal scale, it is impossible to determine which individual has the larger score. (T/F)
True
In an introductory theater class, the professor records from the number of movies students watched the previous year. The teacher is measuring a discrete variable. (T/F)
True
In the experimental method, the researchers manipulates the independent variable (T/F)
True
To compute (ΣX)2, you first add the scores, then square the total. (T/F)
True
What is the value of ΣX2 for the following scores? Scores: 1, 0, 2, 4 A.) 14 B.) 21 C.) 28 D.) 49
B.) 21
What term is used to describe the shape of a distribution in which the scores pile up on the left-hand side of the graph and taper off to the right? A.) symmetrical B.) positively skewed C.) negatively skewed D.) normal
B.) positively skewed
In a population of N = 6, five of the individuals all have scores that are exactly 1 point above the mean. From this information, what can you determine about the score for the sixth individual? A. It is also above the mean by 1 point. B. It is below the mean by 1 point. C. It is below the mean by 5 points. D. It is equal to the mean.
C. It is below the mean by 5 points.
What is the shape of the distribution for the following set of data? Scores: 1, 2, 3, 3, 4, 4, 4 5, 5, 5, 5, 6 A.) symmetrical B.) positively skewed C.) negatively skewed D.) cumulative
C.) negatively skewed
With α = .05, what is the critical t value for a one-tailed test with n = 15? t = 1.753 t = 2.131 t = 1.761 t = 2.145
t = 1.761