STATS Final
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. 10/40 c. 1/10 d. 1/40
b. 10/40
In N = 25 games last season, the college basketball team averaged μ = 76 points with a standard deviation of σ = 6. In their final game of the season, the team scored 89 points. Based on this information, the number of points scored in the final game was ____. a. a little above average b. far above average c. above average, but it is impossible to describe how much above average d. impossible to determine because there is not enough information to compare last year with the average
b. far above average
Which combination of factors is most likely to produce a significant value for an independent-measures t statistic? a. large samples and large variance b. large samples and small variance c. small samples and large variance d. small samples and small variance
b. large samples and small variance
A distribution of scores has a mean of μ = 50. One new score is added to the distribution and the new mean is found to be μ = 48. From this result, you can conclude that the new score was ____. a. greater than 50 b. less than 50 c. equal to 48 d. between 50 and 52
b. less than 50
In a distribution with positive skew, scores with the highest frequencies are ____. a. on the right side of the distribution b. on the left side of the distribution c. in the middle of the distribution d. represented at two distinct peaks
b. on the left side of the distribution
A researcher plans to conduct a research study comparing two treatment conditions with a total of 20 scores in each treatment. Which of the following designs would require only 20 participants? a. independent-measures design b. repeated-measures design c. matched-subjects design d. between-measures design
b. repeated-measures design
What value is estimated with a confidence interval using the repeated-measures t statistic? a. the mean for a sample of difference scores b. the mean for a population of difference scores c. the difference between two population means d. the difference between two sample means
b. the mean for a population of difference scores
What term is used to identify the standard deviation of the distribution of sample means? a. the expected value of M b. the standard error of M c. the sample mean d. the central limit mean
b. the standard error of M
Which of the following is the correct null hypothesis for a repeated-measures t test? a. MD = 0 b. μD = 0 c. μ1 = μ2 d.M1 =M2
b. μD = 0
What happens to the expected value of M as sample size increases? a. It also increases. b. It decreases. c. It stays constant. d. The expected value does not change in a predictable manner when sample size increases.
c. It stays constant.
What is the probability of randomly selecting a z-score greater than z = 0.75 from a normal distribution? a. 0.7734 b. 0.2266 c. 0.2734 d. 0.4532
b. 0.2266
An independent-measures study with n = 6 in each sample, produces a sample mean difference of 4 points and a pooled variance of 12.What is the value for the t statistic? a. 1 b. 2 c. 4/6 d. 4/8
b. 2
For a perfectly symmetrical distribution with a median of 30, what is the value of the mean? a. greater than 30 b. 30 c. 20 to 29.5 d. less than 20
b. 30
Which of the following statements is TRUE? A. A measure can but reliable but not very valid. B. A measure can be valid but not very reliable. C. Both A & B are possible D. Both A & B are impossible
A. A measure can but reliable but not very valid.
A representative sample is most necessary for which type of claim? A. Causal B. Frequency C. Association D. Construct
A. Causal
The clinician gives his measure to 3 colleagues who are also experts in pathological gambling. All colleagues say that his measure appears to test all the components of pathological gambling, including feeling restless when attempting to stop gambling, jeopardizing jobs in order to keep gambling, and using gambling to escape from a bad mood. Given this information, this measure has evidence of which of the following? A. Content validity B. Predictive validity C. Concurrent validity D. Discriminant validity
A. Content validity
The purpose of peer review is to A. Ensure that only high-quality studies get published B. Enforce penalties for unethical research practice C. Develop ethical principle and guidelines for researchers D. Generate ideas of how to utilize basic research in applied research
A. Ensure that only high-quality studies get published
Both James and Thomas have theories that explain why listening to classical music while reading is associated with increased recall of the material. James's theory is much simpler than Thomas's. Thomas created his theory a few months before James did. Which of the following is true? A. James's theory would be considered better because it is more parsimonious. B. James's theory would be considered better because it was developed more recently. C. Thomas's theory would be considered better because he developed it first. D. Thomas's theory would be considered better because it is more complex.
A. James's theory would be considered better because it is more parsimonious.
An experiment to measure participants' reaction time (in seconds) to press a button upon seeing a sad picture on the computer screen is designed. Which scale of measurement is reaction time? A. Ratio B. Nominal C. Interval D. Ordinal
A. Ratio
A developmental psychologist, is planning a study that involves watching children play together to determine how sharing behavior occurs in same-sex friend pairs compared with opposite-sex friend pairs. The researcher reports that a concern that the children will behave differently because of the presence of the research assistants. This is a concern about: A. Reactivity B. Bystander effects C. Observer bias D. Interrater reliability
A. Reactivity
Dr. Prichard wanted to investigate whether taking a test with pencil versus pen had an effect on overall test score. She identified two specific classes (both introduction to psychology courses) which each met Tuesday/Thursdays from 2:00-3:50pm. She had the two professors each administer the same psychology exam to their students on the same day at the same time. Which of the following statements is true? A. The study has low internal validity due to multiple confounds B. Utilizing confederates in this study increases the construct validity C. Causal conclusions can be made due to the experimental design D. The researcher will need to assess interrater-reliability
A. The study has low internal validity due to multiple confounds
Dr. Alfonse, a developmental psychologist, conducts a study to determine whether children prefer books with drawn illustrations or with photographs. A group of 45 first graders are shown two copies of a book (Little Red Riding Hood) at the same time. Although the story is the same, one book is illustrated with drawings and the other is illustrated with photos. Students are then asked to indicate which book they prefer. This is an example of which of the following designs? A. Pretest-posttest design B. Concurrent-measures design C. Repeated-measures design D. Posttest-only design
B. Concurrent-measures design
If the measure does not actually measure pathological gambling, this measure is said to lack which of the following? A. Internal Validity B. Construct Validity C. Reliability D. Operationalization
B. Construct Validity
A correlation-based statistic called Cronbach's alpha is commonly used to determine ________. A. Interrater reliability B. Internal reliability C. Test-retest reliability D. Construct reliability
B. Internal reliability
Before using the Narcissus Scale in the study, the data from students who acted as test participants are analyzed. The researcher looks for the relationship between each of the individual questions, and sees that participants who agreed with Question 1 also agreed with Question 2 and disagreed with Question 3. Which of the following is being evaluated? A. Interrater reliability B. Internal reliability C. Test-retest reliability D. Construct reliability E. None of the above
B. Internal reliability
In developing a measure of "need for cognition" (a trait that describes the degree to which people like thinking and problem-solving), a researcher asks participants to rate their agreement with the following statement: "I frequently solve and enjoy solving crossword puzzles and Sudoku puzzles." What is the problem with this question? A. It is a forced-choice question. B. It is a double-barreled question. C. It has a double negative question. D. None of the above are problems with this question.
B. It is a double-barreled question.
A researcher wanted to evaluate the effectiveness of a medication treatment for depression. Participants are randomly assigned to either the control group or the experimental group. The participants complete a self-report depression measure before and then after the treatment. Which statement is FALSE? A. Giving the control group a placebo pill will increase internal validity B. Participants' pre-treatment depression scores should be correlated with their post-treatment depression scores. C. The study is a between-groups design because each participant is exposed to only one level D. Recruiting a large number of participants would benefit this study.
B. Participants' pre-treatment depression scores should be correlated with their post-treatment depression scores.
A researcher finds a correlational relationship between the number of hours of sleep one gets and problem-solving ability. Specifically, having a lower amount of sleep the night before an exam is associated with lower scores on a problem-solving test. This is an example of which type of correlation? A. Negative correlation B. Positive correlation C. Zero correlation D. There is not enough information to answer this question
B. Positive correlation
To test this measure, the clinician administers it to a group of his patients, and at the same time, he asks them how many times they have been gambling in the past month. The prediction being that patients who score higher on the measure will also report gambling more times in the past month. This procedure is meant to provide evidence for which of the following? A. Content validity B. Predictive validity C. Concurrent validity D. Convergent validity
B. Predictive validity
In Roediger & McDermott's 1995 article false memories were operationally defined by: A. The percent correct words recalled or recognized B. Recalling words not studied, but related to words on the lists C. They did not operationally define false memories D. People providing incorrect testimony in court cases
B. Recalling words not studied, but related to words on the lists
According to Peirce, what method of belief relies on unquestioning traditions or habits? A. A Priori B. Tenacity C. Authority D. Scientific method
B. Tenacity
A researcher observed that preschool children playing in a red room showed more aggression than preschool children playing in a blue room. Assuming that this study used an experimental design, what are the independent and dependent variables (in that order)? A. preschool children and color of room B. color of the room and amount of aggression C. the children's play and amount of aggression D. amount of aggression and color of the room
B. color of the room and amount of aggression
The presence of a confounding variable in an experiment is undesirable because A. attrition is likely to occur B. the experimenter cannot be sure if the results are due to the confounding variable or the independent variable C. it increases the number of participants required for each of the groups D. the use of a t-test is impossible
B. the experimenter cannot be sure if the results are due to the confounding variable or the independent variable
Which of the following is necessary to make a causal claim? A. There must be a frequency claim first. B. The 2 variables must be manipulated. C. A true experiment needs to be conducted. D. The 2 variables must be measured.
C. A true experiment needs to be conducted.
Now the clinician wants to test the measure on some university students. A group of 100 university students complete the measure. They also complete two other measures (one that assesses addictive behavior in general and one that assesses inability to resist gambling). They find that this new measure is positively correlated with each of these other measures. This procedure has provided evidence for the _________ of the new measure. A. Discriminant validity B. Criterion-related validity C. Convergent validity D. Content validity
C. Convergent validity
A researcher discovers that a clock used to measure reaction times will (a) measure reaction time consistently, but (b) give the wrong reaction time by adding 20 milliseconds to the actual reaction time. Which of the following properties are true about the clock? A. High validity and high reliability B. High validity and low reliability C. Low validity and high reliability D. Low validity and low reliability
C. Low validity and high reliability
A researcher is curious as to whether falling asleep in front of a television set causes people to fall asleep more slowly compared to when falling asleep without the TV on. A sample of 60 middle-aged women from a local church who reported no history of sleep problems are recruited. The experiment has three conditions. All participants come to the sleep lab for three nights in a row and experience all three conditions. In the first condition (A), participants fall asleep in front of a television that is off. In the second condition (B), participants fall asleep in front of a television that is turned on to the same 24-hour news channel. In the third condition (C), participants fall asleep in front of a television that is turned on to the same 24-hour news channel but is muted. With the use of an electroencephalograph (EEG), the researcher measures how long it takes participants to fall asleep each night. Which of the following designs is being used? A. Pretest/posttest design B. Concurrent-measures design C. Repeated-measures design D. Posttest-only design
C. Repeated-measures design
In an experiment, random assignment increases... A. The covariance of the study B. The temporal precedence of the study C. The internal validity of the study D. The external validity of the study
C. The internal validity of the study
Winston's concern is addressing which of the following? A. The study's statistical validity B. The study's internal validity C. The study's external validity D. The study's construct validity
C. The study's external validity
What can we conclude about the independent and dependent variables based on the below scatterplot? A. The two variables are negatively correlated B. The two variables are positively correlated C. The two variables are not correlated D. The independent variable causes the dependent variable
C. The two variables are not correlated
Research is conducted that demonstrates rats associate fear with places where aversive stimuli are encountered, this research is an example of: A. Applied research B. Construct research C. Abstract research D. Basic research
D. Basic research
What is the advantage of within-subjects design? A. Participants exposed to the first condition will be equivalent in their baseline characteristics compared to participants exposed to the second condition. B. They require fewer participants C. It is less time-consuming for the participants D. Both A and B E. Both B and C
D. Both A and B
Professor Kramer has decided to measure how happy his students are with his teaching this semester. His survey has the following questions: How easy did you feel this class was? 1 2 3 4 5 Which of the questions above is an example of a question that uses a Likert scale? A.Question B B. Question C C. Question D D. Both B and D
D. Both B and D
Order effects can be controlled by using which of the following techniques? A. Random assignment B. Design confounds C. Increasing demand characteristics D. Counterbalancing
D. Counterbalancing
Which of the following is a threat to internal validity found in within-subjects designs but not in between-subjects designs? A. Selection effects B. Counterbalancing C. Non-randomassignment D. Order effects
D. Order effects
The belief that the participants in a research study should be representative of the type of people who would also benefit from the findings of the research stems from which principle of the Belmont Report? A. The Principle of Justice B. The Principle of Respect for Persons C. The Principle of Fidelity D. The Principle of Beneficence E. The Principle of Integrity
D. The Principle of Beneficence
In addition to the three principles derived from the Belmont Report, which of the following two principles were added to the principles put forth by the American Psychological Association? A. The Principles of Consent/Respect and Honesty B. The Principles of Respect and Reliability/Validity C. The Principles of Beneficence/Nonmaleficence and Justice D. The Principles of Integrity and Fidelity/Responsibility
D. The Principles of Integrity and Fidelity/Responsibility
Edward believes that there are a lot of differences between men and women on a variety of different dimensions. He believes this because whenever he thinks about books that have been written on men and women, he can only recall books that claim men and women are very different (e.g., "Men Are from Mars, Women Are from Venus") and cannot recall any that claim that men and women are similar. Edward's reliance on what comes to mind is an example of... A. Cherry-picking of evidence B. The present/absent bias C. Confirmatory hypothesis testing D. The availability heuristic
D. The availability heuristic
Nick's concern is addressing which of the following? A. The study's statistical validity B. The study's internal validity C. The study's external validity D. The study's construct validity
D. The study's construct validity
People with schizophrenia have a problem labeling their emotions. Using this information, a research study is designed to examine whether teaching schizophrenic patients to label the emotions of characters in movie clips helps them to better label their own emotions. This is an example of: A. Basic research B. Theory research C. Peer-reviewed research D. Translational research
D. Translational research
A repeated-measures (within-subjects) design reduces the error variability associated with ______________. A. degrees of freedom B. treatment effects C. experimental error D. individual differences
D. individual differences
Which correlation coefficient represents the strongest correlational relationship? A. r = 0.8 B. r = 0.5 C. r = 0.0 D. r = -0.9
D. r = -0.9
If the null hypothesis is true, what value is expected, on average, for the repeated-measures t statistic? a. 0 b. 1 c. 1.96 d. t > 1.96
a. 0
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. 0.30 b. 0.70 c. p > 0.70 d. 0.40
a. 0.30
A sample consists of n = 16 scores. How many of the scores are used to calculate the range? a. 2 b. 4 c. 8 d. 16
a. 2
The data from an independent-measures research study produce a sample mean difference of 4 points and a pooled variance of 16.If there are n = 8 scores in each sample, then what is the estimated standard error for the sample mean difference? a. 2 b. 4 c. 16 d. 128
a. 2
The sum of the squared deviation scores is SS = 20 for a population of N = 5 scores. What is the variance for this population? a. 4 b. 5 c. 80 d. 100
a. 4
For a sample with M = 50 and s = 12, what is the X value corresponding to z = -0.25? a. 47 b. 53 c. 46 d. 54
a. 47
Which set of characteristics will produce the smallest value for the estimated standard error? a. A large sample size and a small sample variance b. A large sample size and a large sample variance c. A small sample size and a small sample variance d. A small sample size and a large sample variance
a. A large sample size and a small sample 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 big c. If the sample size is small and the sample variance is big d. If the sample size and the sample variance are both small
a. If the sample size is big and the sample variance is small
For the independent-measures t statistic, what is the effect of increasing the difference between sample means? a. Increase the likelihood of rejecting H0 and increase measures of effect size. b. Increase the likelihood of rejecting H0 and decrease measures of effect size. c. Decrease the likelihood of rejecting H0 and increase measures of effect size. d. Decrease the likelihood of rejecting H0 and decrease measures of effect size.
a. Increase the likelihood of rejecting H0 and increase measures of effect size.
A sample of n = 4 scores has a mean of M = 8. If one new score with a value of X = 3 is added to the sample, what will be the value for the new mean? a. M = 7.0 b. M = 8.0 c. M = 8.8 d. M=11.0
a. M = 7.0
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. Spanish c. English d. Grades are the same.
a. Math
An independent-measures research study uses two samples, each with n = 12 participants.If the data produce a t statistic of t = 2.08, then which of the following is the correct decision for a two-tailed hypothesis test? a. Reject the null hypothesis with α = .05 but fail to reject 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. It cannot be answered without additional information.
a. Reject the null hypothesis with α = .05 but fail to reject with α = .01
An independent-measures research study uses two samples, each with n = 12 participants. If the data produce a t statistic of t = 2.50, then which of the following is the correct decision for a two-tailed hypothesis test? a. Reject the null hypothesis with α = .05 but fail to reject 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. It cannot be answered without additional information.
a. Reject the null hypothesis with α = .05 but fail to reject with α = .01.
A researcher expects a treatment to produce an increase in the population mean. The treatment is evaluated using a one tailed hypothesis test, and the test produces z = +1.85, which has p = 0.0322 in the tail. Based on this result, what is the correct statistical decision? a. The researcher should reject the null hypothesis with α = .05 but not with α = .01. b. The researcher should reject the null hypothesis with either α = .05 or α = .01. c. The researcher should fail to reject H0 with either α = .05 or α = .01. d. The researcher should change α.
a. The researcher should reject the null hypothesis with α = .05 but not with α = .01.
Scores on the SAT form a normal distribution with a mean of μ = 500 with σ = 100. If the state college only accepts students who score in the top 60% on the SAT, what is the minimum score needed to be accepted? a. X = 475 b. X = 525 c. X = 440 d. X = 560
a. X = 475
A sample of difference scores has a mean of MD = 5 with a variance of s2 = 100. If effect size is measured using Cohen's d, what is the value of d? a. d = 5/10 b. d = 5/100 c. d = 25/100 d. This cannot be determined without knowing the sample size.
a. d = 5/10
What term is used to identify the mean of the distribution of sample means? a. the expected value of M b. the standard error of M c. the sample mean d. the central limit mean
a. the expected value of M
In a sample with M = 40 and s = 8, what is the z-score corresponding to X = 38? a. z = -0.25 b. z = -0.50 c. z = 0.25 d. z = 0.50
a. z = -0.25
Which of the following is the correct null hypothesis for an independent-measures t test? a. μ1 - μ2 = 0 b.M1 -M2 =0 c. μ1 - μ2 ≠ 0 d.M1 -M2 ≠0
a. μ1 - μ2 = 0
Which set of sample characteristics is most likely to produce a significant value for the independent- measures t statistic? a. A small mean difference and small sample variances b. A large mean difference and small sample variances c. A small mean difference and large sample variances d. A large mean difference and large sample variances
b. A large mean difference and small sample variances
If other factors are held constant, how does sample size influence the likelihood of rejecting the null hypothesis and measures of effect size such as r2 and Cohen's d? a. A larger sample increases both the likelihood and measures of effect size. b. A larger sample increases the likelihood but has little influence on measures of effect size. c. A larger sample decreases the likelihood but has little influence on measures of effect size. d. A larger sample decreases both the likelihood and measures of effect size.
b. A larger sample increases the likelihood but has little influence on measures of effect size.
What happens to the standard error of M as sample size increases? a. It also increases. b. It decreases. c. It stays constant. d. The standard error does not change in a predictable manner when sample size increases.
b. It decreases.
In general, if the variance of the difference scores increases, then what will happen to the value of the t statistic? a. It will increase (move farther toward the tail of the distribution). b. It will decrease (move toward 0 at the center of the distribution). c. It will stay the same; the t statistic is not affected by the variance of the difference scores. d. It may increase or may decrease. There is no consistent relationship between variance and the size of the t statistic.
b. It will decrease (move toward 0 at the center of the distribution).
A sample of n = 4 scores is obtained from a population with μ = 70 and σ = 8. If the sample mean corresponds to a z- score of 2.00, then what is the value of the sample mean? a. M = 86 b. M = 78 c. M = 74 d. M = 72
b. M = 78
What are the values for SS and variance for the following sample of n = 3 scores? Sample: 1, 4, 7 a. SS = 18 and variance = 6 b. SS = 18 and variance = 9 c. SS = 66 and variance = 22 d. SS = 66 and variance = 33
b. SS = 18 and variance = 9
The results of an independent-measures research study are reported as "t(20) = 2.12, p < .05, two tails."For this study, what t values formed the boundaries for the critical region? a. ±2.093 b. ±2.086 c. ±2.080 d. ±2.074
b. ±2.086
Why are t statistics more variable than z-scores? a. The extra variability is caused by variations in the sample mean. b. The extra variability is caused by variations in the sample variance. c. The extra variability is caused by variations in the df value. d. The extra variability is caused by the large sample size.
b. The extra variability is caused by variations in the sample variance.
Two samples from the same population both have M = 84 and s2 = 20; however, one sample has n = 10 and the other has n = 20 scores. Both samples are used to evaluate a hypothesis that μ = 80 and to compute Cohen's d. How will the outcomes for the two samples compare? a. The larger sample is more likely to reject the hypothesis and will produce a larger value for Cohen's d. b. The larger sample is more likely to reject the hypothesis but the two samples will have the same value for Cohen's d. c. The larger sample is less likely to reject the hypothesis and will produce a larger value for Cohen's d. d. The larger sample is less likely to reject the hypothesis but the two samples will have the same value for Cohen's d.
b. The larger sample is more likely to reject the hypothesis but the two samples will have the same value for Cohen's d.
What value is estimated with a confidence interval using the t statistic? a. The value for an unknown sample mean b. The value for an unknown population mean c. The difference between two population means d. The difference between two sample means
b. The value for an unknown population mean
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 decrease (move closer to zero). c. They would stay the same. d. There is not enough information to answer.
b. They would decrease (move closer to zero).
A research report describing the results from a repeated-measures t test states, "t(22) = 1.71, p > .05." From this report you can conclude that the outcome of the hypothesis test was to ____. a. 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 c. reject the null hypothesis with a sample of n = 22 participants d. 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
A researcher administers a treatment to a sample of participants selected from a population with μ = 80. If the researcher obtains a sample mean of M = 88, given the same sample size, which combination of factors is most likely to result in rejecting the null hypothesis? a. σ = 5 and α = .01 b. σ = 5 and α = .05 c. σ = 10 and α = .01 d. σ = 10 and α = .05
b. σ = 5 and α = .05
A normal distribution has a mean of μ = 100 with σ = 20. If one score is randomly selected from this distribution, what is the probability that the score will have a value between X = 90 and X = 120? a. 0.1498 b. 0.4672 c. 0.5328 d. 0.2996
c. 0.5328
What is the total number of scores for the distribution shown in the following table? X f 4 3 3 5 2 4 1 2 a. 4 b. 10 c. 14 d. 37
c. 14
A sample of n = 4 scores has a standard error of 10 points. For the same population, what is the standard error for a sample of n = 16 scores? a. 1 b. 2.5 c. 5 d. 10
c. 5
Which of the following statements is true for a distribution of scores? a. No score is exactly equal to the mean. b. No score is exactly equal to the median. c. At least one score is exactly equal to the mode. d. At least one score is equal to the median.
c. At least one score is exactly equal to the mode.
A researcher obtains t = 2.35 for a repeated-measures study using a sample of n = 8 participants. Based on this t value, what is the correct decision for a two-tailed test? 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. Change α to α = .10.
c. Fail to reject the null hypothesis with either α = .05 or α = .01.
Which of the following is an accurate definition of a Type II error? a. Rejecting a false null hypothesis b. Rejecting a true null hypothesis c. Failing to reject a false null hypothesis d. Failing to reject a true null hypothesis
c. Failing to reject a false null hypothesis
For an independent-measures t statistic, what is the effect of increasing the number of scores in the samples? a. Increase the likelihood of rejecting H0 and increase measures of effect size. b. Increase the likelihood of rejecting H0 and decrease measures of effect size. c. Increase the likelihood of rejecting H0 and have little or no effect on measures of effect size. d. Decrease the likelihood of rejecting H0 and have little or no effect on measures of effect size.
c. Increase the likelihood of rejecting H0 and have little or no effect on measures of effect size.
Two samples, each with n = 6 subjects, produce a pooled variance of 20.Based on this information, what is the estimated standard error for the sample mean difference? a. 20/6 b. 20/12 c. The square root of (20/6 + 20/6) d. The square root of (20/5 + 20/5)
c. The square root of (20/6 + 20/6)
By selecting a larger alpha level, a researcher is ____. a. attempting to make it more difficult to reject H0 b. less able to detect a treatment effect c. increasing the risk of a Type I error d. decreasing the risk of a Type I error
c. increasing the risk 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 = 25 with s2 = 100 b. n=25withs2 =400 c. n = 100 with s2 = 100 d.n=100withs2 =400
c. n = 100 with s2 = 100
A set of 10 scores has SS = 90. If the scores are a sample, the sample variance is ____ and if the scores are a population, the population variance is ____. a. s2 = 9; σ2 = 9 b. s2 = 9; σ2 = 10 c. s2 = 10; σ2 = 9 d. s2 = 10; σ2 = 10
c. s2 = 10; σ2 = 9
With α = .01 the two-tailed critical region for a t test using a sample of n = 16 subjects would have boundaries of ____. a. t = ±2.602 b. t = ±2.583 c. t = ±2.947 d. t = ±2.921
c. t = ±2.947
What z-score value separates the top 70% of a normal distribution from the bottom 30%? a. z = 0.52 b. z = 0.84 c. z = -0.52 d. z = -0.84
c. z = -0.52
For a population with μ = 80 and σ = 10, what is the z-score corresponding to X = 95? a. +0.25 b. +0.50 c. +0.75 d. +1.50
d. +1.50
A repeated-measures study comparing two treatments with a sample of n = 4 participants produces a mean of M = 18 with SS = 24 for the scores in the first treatment, a mean of M = 14 with SS = 18 for the scores in the second treatment, and a mean of M = 4 with SS = 12 for the difference scores. What is the estimated standard error for the sample mean difference? a. 4 b. 3 c. 2 d. 1
d. 1
A repeated-measures study and an independent-measures study both produced a t statistic with df = 16. How many individuals participated in each study? a. 18 for repeated-measures and 17 for independent-measures b. 18 for repeated-measures and 18 for independent-measures c. 17 for repeated-measures and 17 for independent-measures d. 17 for repeated-measures and 18 for independent-measures
d. 17 for repeated-measures and 18 for independent-measures
If α is held constant at .05, what is the impact of changing the sample size on the critical region and the risk of a Type I error? a. As sample size increases, the critical region expands and the risk of a Type I error increases. b. As sample size increases, the critical region shrinks and the risk of a Type I error increases. c. As sample size increases, the critical region expands and the risk of a Type I error decreases. d. As the sample size increases, the critical region, and the risk of a Type I error remain unchanged.
d. As the sample size increases, the critical region, and the risk of a Type I error remain unchanged.
If the sample mean difference is 3 points, which of the following sets of data would produce the largest value for Cohen's d? a. n = 10 for both samples and a pooled variance of 15 b. n = 20 for both samples and a pooled variance of 15 c. n = 30 for both samples and a pooled variance of 15 d. Cohen's d is the same for all three of the samples.
d. Cohen's d is the same for all three of the samples.
If two samples are selected from the same population, under what circumstances are the two samples guaranteed to have exactly the same t statistic? a. If the samples are the same size and have the same variance b. If the samples are the same size and have the same mean c. If the samples have the same mean and the same variance d. If the samples are the same size and have the same mean and have the same variance
d. If the samples are the same size and have the same mean and have the same variance
A sample has a mean of M = 39.5 and a standard deviation of s = 4.3, and produces a t statistic of t = 2.14. For a two- tailed hypothesis test with α = .05, what is the correct statistical decision for this sample? 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 H0 without more information.
d. It is impossible to make a decision about H0 without more information.
A sample with M = 85 and s = 12 is transformed into z-scores. After the transformation, what are the values for the mean and standard deviation for the sample of z-scores? a. M = 85 and s = 12 b. M = 0 and s = 12 c. M = 85 and s = 1 d. M = 0 and s = 1
d. M = 0 and s = 1
For a sample of n = 30 scores, X = 45 corresponds to z = 1.50 and X = 40 corresponds to z = +1.00. What are the values for the sample mean and standard deviation? a. M = 35 and s = 10 b. M = 30 and s = 15 c. M = 35 and s = 15 d. M = 30 and s = 10
d. M = 30 and s = 10
The normal distribution is ____. a. asymmetric b. skewed to the right c. skewed to the left d. symmetric
d. symmetric
A researcher is conducting an experiment to evaluate a treatment that is expected to increase the scores for individuals in a population which is known to have a mean of μ = 80. The results will be examined using a one-tailed hypothesis test. Which of the following is the correct statement of the null hypothesis? a. μ > 80 b. μ > 80 c. μ < 80 d. μ < 80
d. μ < 80
You have a score of X = 65 on a math exam. The mean score for the class on the exam is μ = 70. Which of the following values for the standard deviation would give you the most favorable position within the class? a. σ = 0 b. σ = 1 c. σ = 5 d. σ = 10
σ = 10