PSY230 Final Study Guide
A positive deviation always indicates a score that is less than the mean. True False
False
A recent study found a correlation between gum disease and heart disease. This result indicates that gum disease causes people to develop heart disease. True False
False
A research report presents the results of an independent-measures ANOVA as follows: F(3, 28) = 5.36, p < .01. This research study compared three treatments. True False
False
A research study compares the mean weight for a sample of n = 36 participants before they begin a 6-week diet and their mean weight at the end of the diet. This is an example of an independent-measures design. True False
False
A student takes a 10-point quiz each week in statistics class. If the student's quiz scores for the first three weeks are 2, 6, and 10, then the mean score is M = 9. True False
False
An experimental research study typically involves measuring two scores for each individual in one group of participants. True False
False
As the sample size is increased, the t distribution becomes flatter and more spread out. True False
False
For any distribution of scores, at least one individual will have a score exactly equal to the mean. True False
False
For the following distribution, 11 people have scores greater than X = 14. X f 20-24 2 15-19 5 10-14 4 5-9 1 True False
False
For the following scores, ΣX2 = 49. Scores: 1, 4, 2, 0 True False
False
If the sample size is equal to the population standard deviation (n = σ), then the standard error for the sample mean is equal to 1.00. True False
False
In a distribution with μ=80 and σ=20, a score of X = 95 corresponds to z = +1.50. True False
False
In a distribution with σ=20, a score that is below the mean by 10 points will have a z-score of z = +0.50. True False
False
Obtaining a significant interaction means that both Factor A and Factor B also have significant main effects. True False
False
The F-ratio for Factor A has df = 1, 40 and the F-ratio for Factor B has df = 3, 40. The F-ratio for the A x B interaction must have must have df = 2, 40. True False
False
The distribution of F-ratios is negatively skewed. True False
False
The probability of randomly selecting a red marble from a jar that contains 10 red marbles and 20 blue marbles is 1/30. True False
False
You can reduce the risk of a Type I error by using a larger sample. True False
False
Define the concept of "sampling error." Note: your definition should include the concepts of sample, population, statistic, and parameter.
The concept of "sampling error" is a way to leave room for any possible cushion mistakes. So say a scientist does a study on the entire population of University of Arizona students: the average GPA among the ENTIRE student body is a 3.2 (made up). Now, if a scientist only does the average based on all nursing students: the average GPA is a 3.8. The sampling error is referring to the difference among any of the data provided during this experiment. The population's data is referred to as a parameter whereas the sample's data is referred to as statistic. The sampling error takes into account the natural difference in a statistic and a parameter.
Explain what is measured by the sign of a z-score and what is measured by its numerical value.
The sign tells whether the score is located above (+) or below (-) the mean. The number identifies the distance from the mean by measuring the number of standard deviations between the score and the mean
Although the size of the sample can influence the outcome of a hypothesis test, it has little or no influence on measures of effect size. True False
True
An F-ratio near 1.00 is an indication that the null hypothesis is likely to be true. True False
True
For a population, a deviation score is computed as X - μ. True False
True
For a repeated-measures study, as the sample mean difference increases, the likelihood of rejecting the null hypothesis also increases. True False
True
For a repeated-measures study, dfbetween treatments = 3 and dftotal = 27. This means that there were n = 7 participants in the study. True False
True
For an independent-measures ANOVA comparing four treatment conditions, dfbetween = 3. True False
True
For an independent-measures t statistic, the estimated standard error measures how much difference is reasonable to expect between the sample means for two samples selected from the same population. True False
True
For an independent-measures two-factor ANOVA, all of the F-ratios use the same denominator. True False
True
For any normal distribution, exactly 97.50% of the z-score values are less than z = +1.96. True False
True
If the 90% confidence interval for μ is from 40 to 50, then the sample mean is M = 45. True False
True
If the two samples are the same size, then the pooled variance will equal the average of the two sample variances. True False
True
In general, the null hypothesis states that the treatment has no effect on the population mean. True False
True
In the repeated-measures t statistic, the value for the estimated standard error in the denominator is computed entirely from the sample data. True False
True
In the second stage of a repeated-measures ANOVA, individual differences are removed from the denominator of the F-ratio. True False
True
On average, a sample of n = 16 scores will provide a better estimate of the population mean than you would get with a sample of n = 9 scores from the same population. True False
True
Post hoc tests such as the Scheffe test are not necessary for an ANOVA comparing only two treatment conditions. True False
True
Repeated-measures designs are particularly well-suited to research studies examining learning or other changes that occur over time. True False
True
The first step in computing Σ(X + 1) is to add 1 point to each score. True False
True
The homogeneity of variance assumption states that the two population variances are equal. True False
True
Using the election results from a sample of n = 100 voters to predict the results for the entire state is an example of inferential statistics. True False
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. True False
True
When the z-score value in a normal distribution is negative, the body is on the right-hand side of the distribution. True False
True
What is assumed by the homogeneity of variance assumption? a) The two populations have equal variances. b) The two population variances are not equal. c) The two samples have equal variances. d) The two sample variances are not equal.
a) The two populations have equal variances.
For the following distribution of quiz scores, How many individuals had a score of X = 2? X f 5 6 4 5 3 5 2 3 1 2 a) 1 b) 3 c) 5 d) Cannot be determined
b) 3
A researcher reports an F-ratio with df = 2, 18 from an independent-measures, single-factor ANOVA. Based on the df values, how many treatments were compared in the study, and what was the total number of subjects participating in the study? a) 3 treatments and 22 subjects b) 3 treatments and 21 subjects c) 2 treatments and 20 subjects d) 2 treatments and 19 subjects
b) 3 treatments and 21 subjects
A population of N = 10 scores has a standard deviation of s = 2. What is the value of SS, the sum of the squared deviations, for this population? a) 2 b) 40 c) 20 d) 4
b) 40
For the scores in the following table, what is the value of ΣX2? X f 4 1 3 2 2 1 1 3 a) 30 b) 41 c) 65 d) 225
b) 41
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) 4 b) 5 c) 100 d) 80
b) 5
Samples of size n = 9 are selected from a population with μ=80 with σ=18. What is the standard error for the distribution of sample means? a) 80 b) 6 c) 18 d) 2
b) 6
Which of the following statements cannot be true for a distribution of scores? a) 60% of the scores are above the mean. b) 60% of the scores are above the median. c) 60% of the scores are above the mode. d) All of the other options are false statements.
b) 60% of the scores are above the median.
One sample has n = 10 scores and a variance of s2= 20, and a second sample has n = 15 scores and a variance of s2= 30. What can you conclude about the pooled variance for these two samples? a) It will be closer to 20 than to 30. b) It will be closer to 30 than to 20. c) It will be exactly halfway between 20 and 30. d) Cannot be determined without more information
b) It will be closer to 30 than to 20.
The average verbal SAT score for the entire class of entering freshmen is 530. However, if you select a sample of 20 freshmen and compute their average verbal SAT score you probably will not get exactly 530. What statistical concept is used to explain the natural difference that exists between a sample mean and the corresponding population mean? a) Inferential error b) Sampling error c) Statistical error d) Parametric error
b) Sampling error
If a researcher is using a t statistic to test a null hypothesis about a population, what information is needed from the population to calculate the t statistic? a) You must know the population mean. b) The t statistic does not require any information about the population. c) You must know the population mean and the variance/standard deviation. d) You must know the population variance/standard deviation.
b) The t statistic does not require any information about the population.
Which combination of factors will produce the largest value for the standard error? a) a large sample and a large standard deviation b) a small sample and a large standard deviation c) a small sample and a small standard deviation d) a large sample and a small standard deviation
b) a small sample and a large standard deviation
Which of the following best describes a hypothesis test? a) an inferential technique that uses information about a population to make predictions about a sample b) an inferential technique that uses the data from a sample to draw inferences about a population c) a descriptive technique that allows researchers to describe a population d) a descriptive technique that allows researchers to describe a sample
b) an inferential technique that uses the data from a sample to draw inferences about a population
Describe the circumstances in which post hoc tests are used, and explain why these tests are necessary.
short answer
List and describe the four steps of a hypothesis test. (Make sure to briefly explain what you are specifically doing during each step!)
short answer
What is a main effect, and what does it mean if a main effect is statistically significant in a two-factor ANOVA? What is an interaction, and what does it mean if an interaction is statistically significant in a two-factor ANOVA?
short answer
What is the purpose for obtaining a measure of central tendency?
short answer
In general, what is the effect of an increase in the variance of difference scores for the sample? a) an increase in the standard error and a decrease in the value of t b) an increase in the standard error and an increase in the value of t c) a decrease in the standard error and an increase in the value of t d) a decrease in the standard error and a decrease in the value of t
a) an increase in the standard error and a decrease in the value of t
For any distribution, what is the z-score corresponding to the mean? a) 0 b) 1 c) N d) Cannot be determined from the information given
a) 0
A sample of n = 9 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 for Cohen's d for this sample? a) 0.50 b) 2.00 c) 1.00 d) 0.33
a) 0.50
A repeated-measures ANOVA has SSwithin treatments = 26 and SSbetween subjects = 12. For this analysis, what is the value for SSerror? a) 14 b) 12 c) 38 d) 26
a) 14
What is the mode for the population of scores shown in the frequency distribution table? X f 5 1 4 2 3 3 2 4 1 2 a) 2 b) 3 c) 3.5 d) 4
a) 2
A sample of n = 4 scores has SS = 60. What is the variance for this sample? a) 20 b) 15 c) 16 d) 30
a) 20
What is the pooled variance for the following two samples? Sample 1: n = 8 and SS = 168 Sample 2: n = 6 and SS = 120 a) 24 b) 7 c) 49 d) 20.57
a) 24
An independent-measures study uses n = 15 participants in each group to compare two treatment conditions. What is the df value for the t statistic in this study? a) 28 b) 29 c) 15 d) 14
a) 28
A researcher reports an F-ratio with df = 2, 40 from a repeated-measures ANOVA. How many treatment conditions were compared in this experiment? a) 3 b) 41 c) 4 d) 2
a) 3
A sample of n = 25 scores has M = 20 and s2 = 9. What is the sample standard deviation? a) 3 b) 4.5 c) 9 d) 81
a) 3
A sample of n = 16 scores produces a t statistic of t = +2.00. If the sample is used to measure effect size with r2, what value will be obtained for r2? a) 4/19 b) 2/19 c) 2/20 d) 4/20
a) 4/19
After every score in a sample is multiplied by 3, the mean is calculated and found to be M = 21. What was the mean for the original scores? a) 7 b) 21 c) 63 d) Cannot be determined from the information given
a) 7
With α=.05, how are the boundaries for the critical region determined in a two-tailed test? a) Boundaries are drawn so there is 2.5% (.025) in each tail of the distribution. b) Boundaries are drawn so there is 5% (.05) in the center of the distribution. c) Boundaries are drawn so there is 5% (.05) in each tail of the distribution. d) Boundaries are drawn so there is 10% (.10) in each tail of the distribution.
a) Boundaries are drawn so there is 2.5% (.025) in each tail of the distribution
Which of the following actions will always change the value of the mean? a) Changing the value of one score b) Adding a new score to the distribution c) Removing a score from the distribution d) All 3 of the other choices are correct
a) Changing the value of one sc
What is the correct denominator for the repeated-measures F-ratio? a) MSerror b) MSbetween treatments c) MSwithin-treatments d) MSbetween subjects
a) MSerror
An exam has 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) Bob, Mary, Sue c) Sue, Bob, Mary d) Mary, Bob, Sue
a) Mary, Sue, Bob
Last week, Sarah had exams in math and in Spanish. On the math exam, the mean was μ=30 with σ=5, and Sarah had a score of X = 45. On the Spanish exam, the mean was μ=60 with σ=8, and Sarah had a score of X = 68. In which class did Sarah perform better, relative to her classmates' performance? a) Math b) Spanish c) Her performance in both classes was equal because the two exam scores are in the same location. d) There is not enough information to determine which the the better performance, relative to classmates.
a) Math
A population with a mean of μ = 6 has ΣX = 54. How many scores are in the population? a) N = 9 b) N = 27 c) N = 6x54 = 324 d) Cannot be determined from the information given
a) N = 9
A two-tailed hypothesis test is being used to evaluate a treatment effect with α=.05. If the sample data produce a z-score of z = -2.24, what is the correct decision? a) Reject the null hypothesis and conclude that the treatment has an effect b) Reject the null hypothesis and conclude that the treatment has no effect c) Fail to reject the null hypothesis and conclude that the treatment has no effect d) Fail to reject the null hypothesis and conclude that the treatment has an effect
a) Reject the null hypothesis and conclude that the treatment has an effect
What is the final step to be performed in the mathematical expression, (ΣX)2? a) Square the sum of the scores b) Square each score c) Add the squared scores d) Add the scores
a) Square the sum of the scores
For an ANOVA comparing three treatment conditions, what is stated by the null hypothesis? a) There are no differences between any of the population means. b) At least one of the three population means is different from another mean. c) All three of the population means are different from each other. d) None of the other choices is correct.
a) There are no differences between any of the population means.
In an independent-measures ANOVA, individual differences contribute to the variance in the numerator and in the denominator of the F-ratio. For a repeated-measures ANOVA, what happens to the individual differences in the numerator of the F-ratio? a) They do not exist because the same individuals participate in all of the treatments. b) They are measured and subtracted out in the second stage of the analysis. c) Individual differences contribute to the variance in the numerator. d) None of the other options accurately describes individual differences in the numerator
a) They do not exist because the same individuals participate in all of the treatments.
When comparing more than two treatment means, why should you use an analysis of variance (ANOVA) instead of using several t tests? a) Using several t tests increases the risk of Type I error. b) Using several t tests increases the risk of Type II error. c) The analysis of variance is more likely to detect a treatment effect. d) There is no advantage to using an analysis of variance instead of several t tests.
a) Using several t tests increases the risk of Type I error.
Under what circumstances is the computational formula preferred over the definitional formula when computing SS, the sum of the squared deviations, for a sample? a) When the sample mean is not a whole number b) When the sample mean is a whole number c) When the sample variance is not a whole number d) When the sample variance is a whole number
a) When the sample mean is not a whole number
The results from a two-factor ANOVA show a significant main effect for Factor A and a significant main effect for Factor B. Based on this information, what can you conclude about the interaction? a) You cannot make any conclusion about the significance of the interaction. b) There is probably a significant interaction. c) The interaction cannot be significant. d) There must be a significant interaction.
a) You cannot make any conclusion about the significance of the interaction.
In an analysis of variance (ANOVA), differences caused by treatment effects contribute to which of the following variances? a) between-treatments variance but not within-treatments variance b) within-treatments variance but not between-treatments variance c) neither between-treatments variance nor within-treatments variance d) both between-treatments variance and within-treatments variance
a) between-treatments variance but not within-treatments variance
Under what circumstances can a very small treatment effect be statistically significant? a) if the sample size is big and the sample variance is small b) if the sample size and the sample variance are both small c) if the sample size is small and the sample variance is big d) if the sample size and the sample variance are both big
a) if the sample size is big and the sample variance is small
Under what circumstances can a very small treatment effect still be significant? a) if the sample size is very large b) if the sample standard deviation is very large c) if the standard error is very large d) all of the above
a) if the sample size is very large
Which of the following accurately describes the critical region? a) outcomes with a very low probability if the null hypothesis is true b) outcomes with a high 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 whether or not the null hypothesis is true
a) outcomes with a very low probability if the null hypothesis is true
What is the purpose of post hoc tests? a) to determine which treatments are significantly different b) to determine how much difference exists between the treatments c) to determine whether or not a Type I error was committed d) to calculate df
a) to determine which treatments are significantly different
A research report describing the results of a repeated-measures t test states that "t(22) = 1.71, p > .05." From this report, what was the outcome of the hypothesis test? a) fail to reject the null hypothesis with a sample of n = 22 participants b) fail to reject the null hypothesis with a sample of n = 23 participants c) reject the null hypothesis with a sample of n = 22 participants d) reject the null hypothesis with a sample of n = 23 participants
b) fail to reject the null hypothesis with a sample of n = 23 participants
If other factors are held constant, which of the following sets of data is most likely to produce a significant value for the repeated-measures t statistic? a) n = 30 and MD = 2 b) n = 30 and MD = 4 c) n = 30 and MD = 2 d) n = 15 and MD = 2
b) n = 30 and MD = 4
Which of the following is the correct null hypothesis for a repeated-measures t test? a) M1 =M2 b) μD = 0 c) μ1 =μ2 d) MD = 0
b) μD = 0
What proportion of a normal distribution is located in the tail beyond z = +1.50? a) 0.4332 b) 0.0668 c) 0.1336 d) 0.9332
b) 0.0668
A normal distribution has μ=20 and σ=4. What is the probability of randomly selecting a score greater than 25 from this distribution? a) 0.3944 b) 0.1056 c) 0.7888 d) 0.8944
b) 0.1056
The following table shows the results of a two-factor ANOVA. Based on this table, what is the value for η2 for Factor A? Source SS df MS F Between 36 3 A 12 1 12 F = 4.00 B 3 1 3 F = 1.00 AxB 21 1 21 F = 7.00 Within 84 28 3 Total 120 31 a) 0.47 b) 0.30 c) 0.18 d) 0.20
b) 0.30
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 less than X = 76? a) 0.1915 b) 0.6915 c) 0.3830 d) 0.3085
b) 0.6915
An analysis of variance (ANOVA) produces SSbetween-treatments = 30, SSwithin-treatments = 60, and an F-ratio with df = 2, 15. For this analysis, what is the F-ratio? a) 60/30 = 2.00 b) 15/4 = 3.75 c) 30/60 = 0.50 d) 4/15 = 0.27
b) 15/4 = 3.75
A sample of n = 25 scores has a mean of M = 40 and a standard deviation of s = 10. What is the estimated standard error for the sample mean? a) 1 b) 2 c) 3 d) 4
b) 2
An independent-measures ANOVA is used to evaluate the mean differences among three treatment conditions with a sample of n = 12 participants in each treatment. For this study, what is the dfbetween treatments? a) 35 b) 2 c) 11 d) 33
b) 2
An independent-measures analysis of variance produces dftotal = 29 and dfwithin treatments = 27. For this analysis, what is dfbetween-treatments? a) 1 b) 2 c) 3 d) cannot be determined without additional information
b) 2
Two samples each have n = 4 scores. If the first sample has a variance of 10 and the second sample has a variance of 6, what is the estimated standard error for the sample mean difference? a) 1 b) 2 c) 4 d) Cannot determine without more information
b) 2
Which of the following research situations would be most likely to use an independent-measures design? a) examine the development of vocabulary as a group of children mature from age 2 to 3 b) compare the mathematics skills for 9th grade boys versus 9th grade girls c) compare the blood-pressure readings before medication and after medication for a group of patients d) examine the long-term effectiveness of a stop-smoking treatment by interviewing participants 2 and 6 months after the treatment ends
b) compare the mathematics skills for 9th grade boys versus 9th grade girls
An independent-measures analysis of variance (ANOVA) is used to evaluate the mean differences for a research study comparing four treatments with a separate sample of n = 8 in each treatment. If the data produce an F-ratio of F = 4.60, which of the following is the correct statistical decision? a) reject the null hypothesis with α=.05 but not with α=.01 b) reject the null hypothesis with either α=.05 or α=.01 c) fail to reject the null hypothesis with either α=.05 or α=.01 d) There is not enough information to make a statistical decision.
b) reject the null hypothesis with either α=.05 or α=.01
A repeated-measures ANOVA for a study comparing three treatment conditions with a sample of n = 10 participants produces an F-ratio of F = 5.40. For this result, which of the following is the correct statistical decision? a) fail to reject the null hypothesis with either α=.05 or α=.01 b) reject the null hypothesis with α=.05 but not with α=.01 c) There is not enough information to determine the correct decision. d) reject the null hypothesis with either α=.05 or α=.01
b) reject the null hypothesis with α=.05 but not with α=.01
With α=.01, the two-tailed critical region for a t test using a sample of n = 16 participants would have boundaries of __________. a) t=±2.602 b) t=±2.947 c) t=±2.583 d) t=±2.921
b) t=±2.947
In an ANOVA, what is represented by the letter N? a) the sum of the scores in a specific treatment b) the number of scores in the total research study c) the number of scores in a specific treatment d) the sum of the scores in the total research study
b) the number of scores in the total research study
In an ANOVA, what is represented by the letter T? a) the sum of the scores in the total research study b) the sum of the scores in a specific treatment c) the number of scores in a specific treatment d) the number of scores in the total research study
b) the sum of the scores in a specific treatment
You are instructed to subtract 4 points from each score and find the sum of the resulting values. How would this set of instructions be expressed in summation notation? a) 4 - ΣX b) Σ(X - 4) c) ΣX - 4 d) Σ(4 - X)
b) Σ(X - 4)
Samples of n = 16 scores are selected from a population. If the distribution of sample means has an expected value of 40 and a standard error of 2, what are the mean and the standard deviation for the population? a) μ=40 and σ=2 b) μ=40 and σ=8 c) μ=40 and σ=32 d) μ=160 and σ=2
b) μ=40 and σ=8
The data from an independent-measures research study produce a sample mean difference of 6 points and an estimated standard error of 2 points. If there are n = 8 scores in each sample, what is the value for the t statistic? a) 6/4 b) 6/0.25 c) 6/2 d) 6/0.50
c) 6/2
Compared to an independent-measures design, a repeated-measures study is more likely to find a significant effect because it reduces the contribution of variance due to __________. a) the effect of the treatment b) time-related factors c) individual differences d) order effects
c) individual differences
On average, what value is expected for the t statistic when the null hypothesis is true? a) 1.96 b) t > 1.96 c) 0 d) 1
c) 0
What is the average value expected for the independent-measures t statistic if the null hypothesis is true? a) 1 b) M1−M2 c) 0 d) +1 or -1
c) 0
IQ scores form a normal distribution with μ=100 and σ=15. Individuals with IQs above 140 are classified in the genius category. What proportion of the population consists of geniuses? a) 0.5038 b) 0.4962 c) 0.0038 d) 0.9962
c) 0.0038
A repeated-measures study comparing two treatments with a sample of n = 4 participants produces MD = 3 with SS = 48 for the set of difference scores. What is the repeated-measures t statistic for these data? a) 0.19 b) 0.75 c) 1.50 d) 1.73
c) 1.50
What is the value of the median for the following set of scores? Scores: 1, 3, 4, 6, 8, 12, 13, 23, 25, 26 a) 12.5 b) 8 c) 10 d) 7
c) 10
What is the range for the following set of scores? Scores: 5, 7, 9, 15 a) 4 points b) 5 points c) 10 or 11 points d) 15 points
c) 10 or 11 points
For the following distribution, what percentage of the individuals have scores of X = 1? X f 5 2 4 8 3 5 2 3 1 2 a) 2% b) 5% c) 10% d) 20%
c) 10%
A repeated-measures study and an independent-measures study both produced a t statistic with df = 10. How many individuals participated in each study? a) 12 for repeated-measures and 11 for independent-measures b) 11 for repeated-measures and 11 for independent-measures c) 11 for repeated-measures and 12 for independent-measures d) 12 for repeated-measures and 12 for independent-measures
c) 11 for repeated-measures and 12 for independent-measures
A population of N = 100 scores has µ = 30 and σ = 4. What is the population variance? a) 4 b) 2 c) 16 d) 8
c) 16
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) 14 b) 15 c) 16 d) Cannot be determined from the information given
c) 16
What is the value of SS (sum of squared deviations) for the following sample? Sample: 1, 3, 2, 2 a) 18 b) 4 c) 2 d) 0.50
c) 2
A repeated-measures study comparing two treatments with n = 4 participants produces MD = 2 and SS = 75 for the difference scores. What is the estimated standard error for the sample mean difference? a) 6.25 b) 25 c) 2.5 d) 5
c) 2.5
A set of scores ranges from a high of X = 24 to a low of X = 5. If these scores were put in a frequency distribution table with an interval width of 2 points, which of the following would be the top interval in the table? a) 4-5 b) 23-24 c) 24-25 d) 22-24
c) 24-25
A repeated-measures experiment compares three treatment conditions with a sample of n = 10 participants. If the data are analyzed with ANOVA, the analysis would have dftotal = __________. a) 27 b) 28 c) 29 d) 30
c) 29
The following table shows the results of an analysis of variance (ANOVA) comparing three treatments. What is the value of η2, the percentage of variance accounted for, for these data? Source SS df MS F Between-treatments 30 2 15 F = 7.50 Within-treatments 60 30 2 Total 90 32 a) 2/30 = .067 b) 30/60 = .5 c) 30/90 = .33 d) 60/90 = .67
c) 30/90 = .33
A researcher obtains t(20) = 2.00 and MD = 9 for a repeated-measures study. If the researcher measures effect size using the percentage of variance accounted for, what value will be obtained for r2? a) 9/29 b) 9/20 c) 4/24 d) 4/13
c) 4/24
What is the median for the following set of scores? Scores: 1, 2, 6, 11, 17 a) 4 b) 8.5 c) 6 d) 8
c) 6
A population of scores has μ=44. In this population, a score of X = 40 corresponds to z = -0.50. What is the population standard deviation? a) 2 b) 4 c) 8 d) -8
c) 8
Students in an introductory art class are classified as art majors and non-art majors. What scale of measurement is being used to classify the students? a) Ordinal b) Ratio c) Nominal d) Interval
c) Nominal
Determining the class standing (1st, 2nd, and so on) for the graduating seniors at a high school would involve measurement on a(n) _____ scale of measurement. a) nominal b) ratio c) interval d) ordinal
d) ordinal
A sample of n = 25 scores produces a t statistic of t = +2.062. If the researcher is using a two-tailed test, which of the following is the correct statistical decision? a) The researcher can reject the null hypothesis with α=.05 but not with α=.01 b) The researcher can reject the null hypothesis with either α=.05 or α=.01 c) The researcher must fail to reject the null hypothesis with either α=.05 or α=.01 d) It is impossible to make a decision about the null hypothesis without more information.
c) The researcher must fail to reject the null hypothesis with either α=.05 or α=.01
A two-factor research study is used to evaluate the effectiveness of a new blood-pressure medication. In this two-factor study, Factor A is medication versus no medication and Factor B is male versus female. The medicine is expected to reduce blood pressure for both males and females, but it is expected to have a much greater effect for males. What pattern of results should be obtained if the medication works as predicted? a) a significant main effect for Factor A (medication) b) a significant interaction c) a significant main effect for Factor A and a significant interaction d) none of these
c) a significant main effect for Factor A and a significant interaction
What position in the distribution corresponds to a z-score of z = -1.00? a) below the mean by 1 point b) above the mean by a distance equal to 1 standard deviation c) below the mean by a distance equal to 1 standard deviation d) above the mean by 1 point
c) below the mean by a distance equal to 1 standard deviation
An effect size (Cohen's d) of .80 is generally considered to be a __________ effect size. a) small b) medium c) large d) not enough information to answer
c) large
If the mean and variance are computed for each sample in an independent-measures, two-factor experiment, which of the following types of sample data will tend to produce large F-ratios for the two-factor ANOVA? a) large differences between sample means and large sample variances Incorrect Response b) small differences between sample means and large sample variances c) large differences between sample means and small sample variances d) small differences between sample means and small sample variances
c) large differences between sample means and small sample variances
A researcher conducts a hypothesis test using a sample from an unknown population. If the t statistic has df = 30, how many individuals were in the sample? a) n = 29 b) n = 30 c) n = 31 d) Cannot be determined from the information given
c) n = 31
Which of the following z-score values represents the location farthest from the mean? a) z = -1.00 b) z = +1.00 c) z = -2.00 d) z = +0.50
c) z = -2.00
The results of an independent-measures research study are reported as "t(22) = 2.12, p < .05, two tails." For this study, what t values formed the boundaries for the critical region? a) ±2.080 b) ±2.064 c) ±2.074 d) ±2.069
c) ±2.074
What symbol is used to identify the standard error of M? a) μ b) σ c) σM d) MM
c) σM
An independent-measures research study uses two samples, each with n = 15 participants. If the data produce a t statistic of t = +2.76, which of the following is the correct decision for a two-tailed hypothesis test? a) Cannot answer without additional information b) fail to reject the null hypothesis with either α = .05 or α = .01 c) reject the null hypothesis with either α = .05 or α = .01 d) reject the null hypothesis with α = .05 but fail to reject with α = .01
d) reject the null hypothesis with α = .05 but fail to reject with α = .01
For a population with μ=80 and σ=8, what is the z-score corresponding to X = 82? a) +0.75 b) +1.25 c) +0.25 d) +1.50
d) +1.50
A normal distribution has a mean of μ=100 and σ=20. If one score is randomly selected from this distribution, what is the probability that the score will have a value between X = 80 and X = 100? a) 0.6826 b) 0.1587 c) 0.8413 d) 0.3413
d) 0.3413
What proportion of a normal distribution is located between z = 0 and z = +1.50? a) 0.9332 b) 0.0668 c) 0.8664 d) 0.4332
d) 0.4332
On average, what value is expected for the F-ratio if the null hypothesis is true? a) k - 1 b) 0 c) N - k d) 1.00
d) 1.00
Which set of scores has the smallest standard deviation? a) 27, 105, 10, 80 b) 5, 11, 42, 22 c) 11, 17, 31, 53 d) 145, 143, 145, 147
d) 145, 143, 145, 147
A single-factor analysis of variance (ANOVA) produces SSbetween-treatments = 40 and MSbetween-treatments = 20. In this analysis, how many treatment conditions are being compared? a) 2 b) 4 c) 20 d) 3
d) 3
For a single-factor independent-measures ANOVA comparing three treatments with a sample of n = 5 in each treatment, what is the critical value for the F-ratio using α=.05? a) 3.88 b) 3.34 c) 3.74 d) 3.49
d) 3.49
A two-factor study with two levels of Factor A and three levels of Factor B uses a separate group of n = 5 participants in each treatment condition. How many participants are needed for the entire study? a) 5 b) 10 c) 25 d) 30
d) 30
A sample is selected from a population with μ=50 and σ=12. If the sample mean of M = 56 produces a z-score of z = +1.00, then how many scores are in the sample? a) 9 b) 2 c) 16 d) 4
d) 4
A sample of n = 100 scores is selected from a population with μ=80 and σ=20. On average, how much error is expected between the sample mean and the population mean? a) 0.8 points b) 2 points c) 0.2 points d) 4 points
d) 4 points
By selecting a larger alpha level, a researcher is _________. a) attempting to make it easier to reject H0 b) better able to detect a treatment effect c) increasing the risk of Type I error d) All of the above options are the result of selecting a larger alpha level.
d) All of the above options are the result of selecting a larger alpha level.
For the following frequency distribution of exam scores, what is the lowest score on the exam? X f 90-94 3 85-89 4 80-84 5 75-79 2 70-74 1 a) X = 70 b) X = 74 c) X = 90 d) Cannot be determined
d) Cannot be determined
For the following frequency distribution, what is ΣX? X f 30-34 1 25-29 1 20-24 3 15-19 2 10-14 1 a) 8 b) 90 c) 110 d) Cannot be determined
d) Cannot be determined
A sample has a mean of M = 86. If one new person 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
d) Cannot be determined from the information given
Which types of graphs are used for data from an interval scale? a) Polygons and bar graphs b) Histograms and bar graphs c) Histograms, bar graphs, and polygons d) Histograms and polygons
d) Histograms and polygons
Under what circumstances will the distribution of sample means be normal? a) Only if the sample size is greater than 30 b) Only if the population distribution is normal c) It is always normal. d) If the population is normal or if the sample size is greater than 30
d) If the population is normal or if the sample size is greater than 30
Which of the following is expected if the null hypothesis is true for an ANOVA? a) MSbetween should be about the same size as MStotal b) SSbetween should be about the same size as SSwithin c) SSbetween should be about the same size as SStotal d) MSbetween should be about the same size as MSwithin
d) MSbetween should be about the same size as MSwithin
In an analysis of variance (ANOVA), which of the following is determined by the size of the sample mean differences? a) dfwithin b) SSwithin c) dfbetween d) SSbetween
d) SSbetween
Which of the following is 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 number of children in a family d) The amount of time to solve a problem
d) The amount of time to solve a problem
A normal distribution has a mean of μ=80 with σ=20. What score separates the lowest 30% of the distribution from the rest of the scores? a) X = 90.4 b) X = 50 c) X = 110 d) X = 69.6
d) X = 69.6
In a repeated-measures ANOVA, the within-treatments variability is divided into two components. What are they? a) between-subjects and between-treatments b) between-treatments and error c) total variability and error d) between-subjects and error
d) between-subjects and error
For which of the following situations would a repeated-measures research design be appropriate? a) comparing self-esteem for students who participate in school athletics versus those who do not b) comparing verbal problem solving skills for science majors versus art majors c) comparing mathematical skills for girls versus boys at age 10 d) comparing pain tolerance with and without acupuncture needles
d) comparing pain tolerance with and without acupuncture needles
For an experiment comparing two methods of teaching social skills training to autistic children, the independent variable is _______ and the dependent variable is _______. a) the autistic children; the social skills that are learned b) teaching methods; the autistic children c) the social skills that are learned; the autistic children d) teaching methods; the social skills that are learned
d) teaching methods; the social skills that are learned
A researcher wants to study how both caffeine and exercise influence sleep, and whether the two interact uniquely to influence sleep. So she recruits 4 groups of participants: Group A has no caffeine and does not exercise before sleep Group B has caffeine, but does not exercise before sleep Group C has no caffeine, but does exercise before sleep Group D has caffeine and exercises before sleep Which of the following research designs is best suited to evaluate the data from this study? a) independent-measures t test b) repeated-measures t test c) single-factor ANOVA d) two-factor ANOVA
d) two-factor ANOVA
A random sample of n = 4 scores is obtained from a population with a mean of μ=80 and a standard deviation of σ=10. If the sample mean is M = 90, what is the z-score for the sample mean? a) z = +20.00 b) z = +1.00 c) z = +5.00 d) z = +2.00
d) z = +2.00