psyc 210
Abel and Kruger (2010) analyzed the smiles of professional baseball players listed in the Baseball Register. The photos of players were classified as either big smiles or no smiles. The age of death for all players were also recorded. The results revealed that players with big smiles lived longer than those with no smiles. Which statistic could be used to determine if there was a significant difference in life span between those with big versus no smiles? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
E. independent samples t
Which of the following Pearson correlations shows the greatest strength or consistency of relationship? A. -0.90 B. +0.74 C. +0.85 D. -0.33
A. -0.90
A researcher measures the following correlation: r = +0.38. What is the value of the coefficient of determination? A. .14 B. .38 C. .62 D. .76
A. .14
A researcher selects two samples of equal size and computes a mean difference of 1.0 between the two sample means. If the pooled sample variance is 4.0, then what is the effect size using the estimated Cohen's d formula? A. 0.25 B. 0.50 C. 1.40 D. not enough information
A. 0.25
The value in the following table are treatment means from a two-factor study. One of the means is missing. What value for the missing mean would result in no main effect for factor A? B1 B2 A1 6 8 A2 12 ? A. 2 B. 10 C. 12 D. 14
A. 2 (because you find the average aka "marginal means" to anticipate main effects and you subtract across if you're anticipating interactions)
A sample of n = 6 scores has a SS = 40. If the same six scores were a population, then the value obtained for the population SS would be _____. A. 40 B. 5(40/4) = 50 C. 4(40/5) = 32 D. 5(40) = 200
A. 40
Scores on the SAT form a normal distribution with mean 500 and standard deviation 100. What is the minimum SAT score needed to be in the top 60% (i.e., 40th percentile) of the distribution? A. 475 B. 525 C. 372 D. 628
A. 475
As a general rule, when the number of intervals needed to summarize a data set is smaller than ___, we can leave the data ungrouped. A. 5 B. 15 C. 20 D. The data should never be grouped.
A. 5
The standardized form of the regression equation is zy = (beta)zx. In the equation, what is beta? (Hint: You may need to revisit output from a simple linear regression using z-scores to answer this question.) A. Beta is equal to the correlation between x and y. B. Beta is equal to SP/SSx C. Beta is equal to r/(n-1) D. Beta is equal to r/n
A. Beta is equal to the correlation between x and y.
Researcher A selects a sample of 20 participants. Researcher B selects a sample of 30 participants. If both samples were selected from the same population, then which researcher selected a sample associated with a larger standard error? A. Researcher A B. Researcher B C. the standard error is the same in both samples
A. Researcher A
Probability can be: A. between 0 and 1 B. between -1 and +1 C. any positive value D. any positive or negative value
A. between 0 and 1
Which of the following will increase the power of a statistical test? A. change alpha from .01 to .05 B. change from a one-tailed test to a two-tailed test C. change the sample size from n = 100 to n = 25 D. None of the options above will increase power.
A. change alpha from .01 to .05
A researcher summarizes a set of data by describing the score that occurred most often. What type of statistics did the researcher use to summarize these data? A. descriptive B. inferential C. analytical D. professional
A. descriptive
The research method used to demonstrate that one variable causes changes in a dependent variable is called the: A. experimental method B. quasi-experimental method C. correlational method D. investigative method
A. experimental method
A Type I error means that the researcher has ____. A. falsely concluded that a treatment has an effect B. correctly concluded that a treatment has no effect C. falsely concluded that a treatment has no effect D. correctly concluded that a treatment has an effect
A. falsely concluded that a treatment has an effect
In a two-factor ANOVA, the F-ratios for factor A, factor B and the interaction of AxB ____. A. may have different df values but they all have the same denominator B. all have the same df values and they all have the same denominator C. may have different df values and may have different denominators D. all may have the same df values but they may have different denominators
A. may have different df values but they all have the same denominator
The range of values for the sample mean that fall within one standard error of the mean in a sampling distribution is M = 39 to M = 43. What is the mean of the sampling distribution, and what is the standard error? A. mean = 41, standard error = 2 B. mean = 39 or 43, standard error = 4 C. mean = 41, standard error = 4 D. the mean and the standard error are unknown
A. mean = 41, standard error = 2
Qualitative variables tend to be on which scale of measurement? A. nominal B. ratio C. interval D. lateral
A. nominal
A binomial distribution has p = q = .5 and n = 100. Using the normal approximation to this distribution, the probability of selecting X < 60 corresponds to ____. A. p(z < 9.5/5) B. p(z < 10/5) C. p(z < 10.5/5) D. p(z < 11/5)
A. p(z < 9.5/5)
What pattern would appear in a graph of a Pearson correlation of r = +0.80? A. points tightly clustered around a line that slopes up to the right. B. points tightly clustered around a line that sloped down to the right. C. points widely scattered around a line that slopes up to the right. D. points widely scattered around a line that slopes down to the right.
A. points tightly clustered around a line that slopes up to the right.
The power of a statistical test is the probability of ___. A. rejecting a true null hypothesis B. supporting a true null hypothesis C. rejecting a false null hypothesis D. supporting a false null hypothesis
A. rejecting a true null hypothesis
What is the limitation in which the range of data for one or both factors in a sample is smaller than the range of data in the larger population? A. restriction of range B. outliers C. correlation D. causality
A. restriction of range
When a decision is to reject the null hypothesis, the result is: A. statistically significant B. statistically non-significant C. insignificant D. both b and c
A. statistically significant
When a Pearson correlation is computed for data measured on an ordinal scale (ranks), the result is known as A. the Spearman correlation. B. the point-biserial correlation. C. the phi coefficient. D. It is still called a Pearson correlation.
A. the Spearman correlation.
A researcher compares the mean difference between two groups with 15 students in each group and reports the following result for an independent groups t-test: t(29) = 3.52, p < .05. If this is a two-tailed test at a .05 level of significance, then what must be incorrect with this result? A. the degrees of freedom B. the value of the test statistic C. the level of significance D. the p value
A. the degrees of freedom
Suppose that data are distributed such that the mean, median, and mode are nearly equal. Which measure of central tendency is most appropriate for these data? A. the mean B. the median C. the mode D. all of the above E. none of the above Reset Selection
A. the mean
A statistical procedure used to compute the slope (b) and y-intercept (a) of the best-fitting line to a set of data points is called: A. the method of least squares B. the method of most squares C. the method of common squares D. the method of data squares
A. the method of least squares
The null hypothesis for an ANOVA states that ___. A. there are no differences between any of the population means B. at least one of the population means is different from the others C. all of the population means are different from each other D. none of the other three choices are correct.
A. there are no differences between any of the population means
A new over-the-counter drug is developed to treat migraines, and the company needs to decide what dosage should be listed on the package. Clinical trials suggest that 10 mg of the drug is effective as long as the patient weighs less than 200 pounds. Suppose the average weight of women is 160 pounds with a standard deviation of 20. Which statistic could be used to determine what percentage of women will be too heavy for the recommended dosage to be effective? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
A. z for a single score
If the verbal portion of the GRE has a mean of μ = 469, with a standard deviation of σ = 120), what statistic could be used to determine the percentage of test takers who obtained scores of 750 or higher (assume scores are normally distributed)? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
A. z for a single score
Which types of graphs are used for data from an interval scale? A. histograms and bar graphs B. polygons and bar graphs C. histograms and polygons D. histograms, bar graphs, and polygons
C. histograms and polygons
The scores on an organic chemistry test were rather low and normally distributed (μ = 53.2, σ = 8.1). The teacher decides to give everyone who scored 2 SDs above the mean an A and everyone who scored to SDs below the mean an F. What statistic should the teacher use to determine which scores on the exam would result in an A and an F? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
A. z for a single score
Without doing any calculations, which of the following samples has the largest variance? A. 1, 3, 4, 5, 6 B. 1, 5, 8, 12, 22 C. 30, 32, 34, 35, 36
B. 1, 5, 8, 12, 22
An analysis of variances produce SSbetween = 20, SSwithin = 30, and an F-ratio with df = 2, 15. For this analysis, what is the F-ratio? A. 20/30 = 0.67 B. 10/2 = 5.0 C. 30/20 = 1.5 D. 2/10 = 0.20
B. 10/2 = 5.0 (because F=MSbetween/MSwithin so you have to do SS/df for both first!)
A researcher conducts a single sample t-test with a sample of 12 participants. What are the degrees of freedom for this hypothesis test? A. 10 B. 11 C. 12 D. 13
B. 11
A video game is fixed such that the probability of losing is p = .70 for each play. What is the standard deviation for this binomial probability distribution if we play 40 times? A. 1.0 B. 2.9 C. 5.0 D. 8.4
B. 2.9
The following table shows the results of a repeated-measures analysis of variance comparing three treatment conditions with a sample of n = 10 participants. Note that several values are missing in the table. What is the missing value for the F-ratio? Source SS df MS Between 28 xx xx F=xx Within xx xx Bet. Sub. 16 xx Error xx xx xx Total 80 xx A. 4 B. 7 C. 10 D. 14
B. 7
If you are randomly selecting one student from a class of 7 males and 23 females, what is the probability of selecting a male? A. 7/23 = .3043 B. 7/30 = .2333 C. 23/30 = .7667 D. 23/7 = 3.2857
B. 7/30 = .2333
Two researchers (A and B) measure the same mean difference between two related groups using the same sample size. The only difference is that the estimated standard error for difference scores is larger for Researcher A's data than for Researcher B's data. Which researcher will compute a larger test statistic for a related samples t-test? A. Researcher A B. Researcher B C. The test statistic will be the same for both researchers
B. Researcher B
A researcher administers a treatment to a sample of n = 25 participants and uses a hypothesis test to evaluate the effect of the treatment. The hypothesis test produces a z-score of z = 2.77. Assuming that the researcher is using a two-tailed test, A. The researcher rejects the null hypothesis with alpha = .05 but not with alpha = .01. B. The researcher should reject the null hypothesis with either alpha = .05 or alpha = .01. C. The researcher should fail to reject the null hypothesis with either alpha = .05 or alpha = .01. D. Cannot answer without additional information.
B. The researcher should reject the null hypothesis with either alpha = .05 or alpha = .01.
A researcher measures the number of votes submitted for each of three candidates. He wants to plot the number of votes along the y-axis and the candidate's names along the x-axis. What type of graph is appropriate for these data? A. a bar chart because the data are quantitative B. a bar chart because the data are qualitative C. a bar chart because the data are not qualitative D. a histogram because the data are quantitative
B. a bar chart because the data are qualitative
Why does the t-distribution have greater variability in the tails of the distribution compared to a normal distribution? A. because the t-distribution is positively skewed B. because the sample variance is substituted for the population variance to estimate the standard error in this distribution C. because the normal distribution is negatively skewed compared to the t-distribution. D. it does not; the t-distribution is the same as a normal distribution
B. because the sample variance is substituted for the population variance to estimate the standard error in this distribution
Which of the following will increase the power of a hypothesis test? A. change alpha from .05 to .01 B. change the sample size from 25 to 100 C. change from a one-tailed test to a two-tailed test D. none of the other options will increase power
B. change the sample size from 25 to 100
A researcher wants to examine the relationship between sleeping habits and grade point average for college students. A group of 100 students is selected and each student is asked to report the average number of hours he/she sleeps each night and his/her grade point average. What research method is being used in this study? A. experimental method B. correlational method C. non-experimental method comparing two groups D. none of the above
B. correlational method
The two general types of statistics are: A. summary; descriptive B. descriptive; inferential C. interpretative; analytical D. simple; complex
B. descriptive; inferential
Which combination of factors will produce a large value for eta-squared in a single factor ANOVA? A. large mean differences and large sample variances B. large mean differences and small sample variances C. small mean differences and large sample variances D. small mean differences and small sample variances
B. large mean differences and small sample variances
If other factors are held constant, which combination of sample characteristics would produce the narrowest interval? A. large sample size (n) with large variance B. large sample size (n) with small variance C. small sample size (n) with large variance D. small sample size (n) with small variance
B. large sample size (n) with small variance
The denominator for sample variance is ___; the denominator for population variance is ___. A. N; n-1 B. n-1; N C. df; N D. both b and c
B. n-1; N
A researcher reports the following result for a z-test at a .05 level of significance: z = 1.88, p = .06 (d = .25). Is this result statistically significant? A. yes, the decision is to reject the null hypothesis B. no, the decision is to fail to reject the null hypothesis C. yes, because the effect size is large D. no, because the effect size is small
B. no, the decision is to fail to reject the null hypothesis
State the four scales of measurement from least to most informative: A. ratio, interval, ordinal, nominal B. nominal, ordinal, interval, ratio C. ordinal, interval, nominal, ratio D. nominal, ratio, ordinal, interval
B. nominal, ordinal, interval, ratio
When I say that the mean is considered the balance point of a distribution, I'm saying that it is: A. always equal to 0 B. not always located at the center of a distribution of scores C. equal to the score in the middle of a distribution of scores D. used to measure the extent to which objects balance
B. not always located at the center of a distribution of scores
For a normal population with a mean of 80 and a standard deviation of 10, what is the probability of obtaining a sample mean greater than M = 75 for a sample of n = 25 scores? A. p = 0.0062 B. p = 0.9938 C. p = 0.3085 D. p = 0.6915
B. p = 0.9938
A researcher records the family relationship (brother, son, father, cousin, etc.) of the people who stay in regular contact with loved ones in a nursing home. What type of measure is family relationship? A. quantitative and discrete B. qualitative and discrete C. qualitative and continuous D. quantitative and continuous
B. qualitative and discrete
A researcher is interested in the eating behavior of rats and selects a group of 25 rats to be tested in a research study. The average score for the group of 25 rats is an example of a _____. A. sample B. statistic C. population D. parameter
B. statistic
One group of new freshman is given a study-skills training course during the first week of college and a second group does not receive the course. At the end of the semester, the grade point average is recorded for each student. For this study, what is the dependent variable? A. receiving or not receiving the course B. the grade point average for each student C. the group that received the training course D. the group that did not receive the course
B. the grade point average for each student
A health psychologist studies food intake by recording two measures: the type of food consumed (high fat, low fat) and the number of calories consumed. Which is a ordinal scale measure? A. the weight of the food B. the type of food consumed C. the number of calories consumed D. both b and c
B. the type of food consumed
A researcher tests the extent to which the wealth of a country, X, can be used to predict the unemployment rate of a nation, Y. Which factor is the criterion variable? A. the wealth of a country B. the unemployment rate of a nation C. both factors are criterion variables in this example.
B. the unemployment rate of a nation
A researcher tests the extent to which the timing of a stimulus presentation, X, can be used to predict the frequency of a behavioral response, Y. Which factor is the predictor variable? A. the frequency of a behavioral response B. timing of a stimulus presentation C. both factors are predictor variables in this example
B. timing of a stimulus presentation
The sample variance is a(n) ____ when, on average, its value is equal to the value of the population variance. A. biased estimator B. unbiased estimator
B. unbiased estimator
Under what circumstances are post hoc tests necessary? A. when you reject the null hypothesis with exactly two treatment conditions. B. when you reject the null hypothesis with more than two treatment conditions. C. when you fail to reject the null hypothesis with exactly two treatment conditions. D. when you fail to reject the null hypothesis with more than two treatment conditions.
B. when you reject the null hypothesis with more than two treatment conditions.
A distribution with mean 35 and standard deviation of 8 is being standardized so that the new mean and standard deviation will be mean = 50 and standard deviation of 10. In the new, standardized distribution your score is x = 60. What was your score in the original distribution? A. x = 45 B. x = 43 C. x = 1.00 D. impossible to determine without more information
B. x = 43
For a normal distribution, what z-score separates the highest 80% of the scores from the rest of the distribution? (80% above, 20% below) A. z = 0.84 B. z = -0.84 C. z = 1.28 D. z = -1.28
B. z = -0.84
For a population with a standard deviation of 6, what is the z-score corresponding to a score that is 12 points above the mean? A. z = 1 B. z = 2 C. z = 6 D. z = 12
B. z = 2
An insurance company keeps careful records of how long all patients stay in the hospital. Analysis of these data reveals that the average length of stay in the maternity ward for women who have had a caesarean section is μ = 3.9 days with a standard deviation of σ = 1.2. A new program has been instituted that provides new parents with at home care from a midwife for 2 days after the surgery. To determine if this program has any effect on the number of days women stay in the hospital, the insurance company computes the length of stay of a sample of 100 women who participate in the new program and find that their mean length of stay is 3.4 with a standard deviation of 1.4. Which statistic would help determine if the new program is effective at lowering the average length of mothers' hospital stay? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
B. z for a sample mean
The proportion of a normal distribution that corresponds to values greater than z = 1.00 is p = 0.1587. What is the proportion that corresponds to values less than z = -1.00? A. 0.8413 B. -0.8413 C. 0.1587 D. -0.1587
C. 0.1587
For a normal distribution with µ = 50 and sigma = 10, what is the probability of randomly selecting a score greater than x = 56? A. 0.3446 B. 0.6554 C. 0.2743 D. 0.7257
C. 0.2743
A research report with a single-factor ANOVA concludes that there are significant differences among treatments, with F(2, 27) = 8.62, p < .01. If the same number of participants was used in all of the treatment conditions, then how many individuals were in each treatment? A. 7 B. 9 C. 10 D. cannot determine without additional information
C. 10
A sample of n = 25 scores is determined to have a standard error of 2 points. What is the standard deviation or the population from which the sample was obtained? A. 2 B. 2/5 C. 10 D. 50
C. 10
The results of a repeated-measures ANOVA are reported as follows, F(3, 27)=1.12, p > .05. How many subjects participated in the study? *****remember for repeated measures the dferror is the second one listed and that equals (n-1)(k-1)***** A. 40 B. 36 C. 10 D. 9
C. 10 because (k-1)(n-1)=27 3(n-1)=27 n-1=9 n=10
A group of 20 participants are observed two times. The related samples t-test for this study will have degrees of freedom equal to: A. 38 B. 18 C. 19 D. 20
C. 19
A researcher conducts a single sample t-test. What are the critical values for a two-tailed hypothesis test at .05 level of significance when df = 14? A. 1.761 B. 1.771 C. 2.145 D. 2.160
C. 2.145
A sample of scores is normally distributed with M = 12 and standard error = 5. What are the upper and lower 95% confidence limits for a one-independent sample z-test? A. 7 to 17 B. 3.8 to 20.2 C. 2.2 to 21.8 D. 10.04 to 13.96
C. 2.2 to 21.8 (because CI=M+ or - [zcrit*SE])
A two-factor ANOVA produces an F-ratio for factor A with df = 2, 36 and an F-ratio for factor B with df = 3, 36. Which of the following describes the experiment producing these F-ratios? A. 1 level of factor A and 2 levels of factor B B. 2 levels of factor A and 2 levels of factor B C. 3 levels of factor A and 4 levels of factor B D. 6 levels for both factors
C. 3 levels of factor A and 4 levels of factor B
For an experiment involving two levels of factor A and 4 levels of factor B with a sample of n = 5 in each treatment condition (or cell), what is the value for df within? A. 23 B. 29 C. 32 D. 39
C. 32 because Factor A has 2 levels and Factor B has 4 levels, so it should look like a 2x8 matrix. For a factorial ANOVA it is: N - k (my notes) or pq(n-1) textbook. N = 5 people in each group times 8 groups total = 40 k = 8 different groups, so 40-8 = 32
Samples of size n = 4 are selected from a population with a mean of 80 and a population standard deviation of 8. What is the standard error for the distribution of sample means? A. 80 B. 8 C. 4 D. 2
C. 4
For a population with a standard deviation of 10, a score of X = 60 corresponds to a z = -1.50. What is the population mean? A. 30 B. 45 C. 75 D. 90
C. 75
An analysis of variance is used to evaluate the mean differences for a research study comparing four treatments with a separate sample of n = 5 in each treatment. If the data produce an F-ratio of F = 3.15, then which of the following is the correct statistical decision? A. reject the null hypothesis with alpha = .05 but not with alpha = .01 B. reject the null hypothesis with either alpha = .05 or alpha = .01 C. Fail to reject the null hypothesis with either alpha = .05 or alpha = .01 D. There is not enough information to make a statistical decision.
C. Fail to reject the null hypothesis with either alpha = .05 or alpha = .01 (because we needed an F of at least 3.24)
For a positively skewed distribution with M = 30, what is the most likely location for the median? A. Equal to 30 B. Greater than 30 C. Less than 30 D. Cannot be determined from the information provided.
C. Less than 30
For a normal population with a mean 80 and standard deviation 20 which of the following sample means is an extreme and unrepresentative value? A. M greater than 90 for a sample of n = 4 B. M greater than 85 for a sample of n = 4 C. M greater than 90 for a sample of n = 25 D. M greater than 85 for a sample of n = 25
C. M greater than 90 for a sample of n = 25
Which of the following is not part of the calculation of a two-factor ANOVA A. MS for A B. MS for AxB C. MS between treatments D. MS within treatments
C. MS between treatments
Which of the following is not normally calculated as part of a one-way ANOVA? A. SStotal B. SSwithin C. MStotal D. MSwithin
C. MStotal
A researcher incorrectly decides to retain a null hypothesis that is actually false. The researcher has committed: A. no error B. Type I error C. Type II error D. Type I and II errors
C. Type II error
Under what circumstances is the phi-coefficient used? A. When one variable consists of ranks and the other is regular, numerical scores. B. When both variables consists of ranks. C. When both X and Y are dichotomous variables. D. When one variable is dichotomous and the other is regular, numerical scores.
C. When both X and Y are dichotomous variables.
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 a 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. This expectation should result in ___. A. a significant main effect for factor A (medication) B. a significant interaction C. a significant main effect for factor A (medication) and a significant interaction D. none of the above
C. a significant main effect for factor A (medication) and a significant interaction
In a line graph showing the results from a two factor experiment, the levels of factor B are presented on the X-axis and, although the line for A1 is crooked, the points on the line are consistently 5 points higher than the line for A2. What result is indicated by this pattern? A. no indication of an interaction B. an indication of an overall A effect C. an indication of an A effect but no indication of an interaction D. an indication of an interaction but no indication of an A effect.
C. an indication of an A effect but no indication of an interaction
For an experiment comparing more than two treatment conditions you should use analysis of variance rather than separate t tests because _____. A. separate t tests would require substantially more computations. B. a test based on variances is more sensitive than a test basd on means. C. conducing several t tests would inflate the risk of a Type I error. D. There is no difference between the two tests, you can use either one.
C. conducing several t tests would inflate the risk of a Type I error.
A repeated measures analysis of variance uses a sample of n = 5 individuals to evaluate the mean differences among three treatments. The ANOVA for this study has A. dfwithin treatments = 4 and dfbetween subjects = 4 B. dfwithin treatments = 14 and dfbetween subjects = 4 C. dfwithin treatments = 12 and dfbetween subjects = 4 D. dfwithin treatments = 12 and dfbetween subjects = 14
C. dfwithin treatments = 12 and dfbetween subjects = 4
Outliers can obscure the relationship between two factors by altering the: A. extent to which two correlations are related to a third factor B. the extent to which changes in one factor cause changes in a second factor C. direction and strength of an observed correlation coefficient D. none of the above
C. direction and strength of an observed correlation coefficient
If the tail of a normal distribution contains exactly 2.5% of the scores, then what is the z-score value that separates the tail from the body of the distribution? A. z = 1.96 B. z = -1.96 C. either z = 1.96 or z = -1.96 D. none of the above is correct
C. either z = 1.96 or z = -1.96
The standard error of the mean is: A. the standard deviation for a sampling distribution B. a measure of the distance the sample means deviate from the population mean C. equal to the population standard deviation divided by the square root of the sample size D. all of the above
C. equal to the population standard deviation divided by the square root of the sample size
A researcher computes a z-test. The test is a non-directional hypothesis test. The critical value is placed: A. in the upper tail of the standard normal distribution B. in the lower tail of the standard normal distribution C. in both tails of the standard normal distribution D. in no tails of the standard normal distribution
C. in both tails of the standard normal distribution
If you have a score of X = 75 on an exam, which set of parameters would give you the highest position within the class? A. mean of 70, standard deviation of 5 B. mean of 70, standard deviation of 10 C. mean of 60, standard deviation of 5 D. mean of 60, standard deviation of 10
C. mean of 60, standard deviation of 5
A researcher records the following time (in seconds) that children in a sample play with an unfamiliar toy: 12, 14, 10, 6, 8, 10, 13, 12, 4, 12, and 6. Which measure of central tendency is largest? A. mean B. median C. mode D. all measures are equal
C. mode
A statistical method that includes two or more predictor variables in the equation of a regression line to predict changes in a criterion variable is called: A. standard regression B. estimate regression C. multiple regression D. two-way regression
C. multiple regression
The median can be used for skewed distributions and ordinal data. Why is the median appropriate for describing ordinal data? A. ordinal data are the only type of data that have a median B. ordinal data are always positively or negatively skewed C. ordinal data convey direction only (more or less than) D. ordinal data convey the same information as ratio data.
C. ordinal data convey direction only (more or less than)
A psychologist is testing people's sense of direction by leading them through a maze in the basement of the psychology building and then asking them to identify which of four directions is north. In a sample of 48 people, 17 correctly identified the direction. In order to calculate the probability that 17 or more people would correctly identify the direction if they were simply guessing, which of the following is true? A. p = .5; q = .5; X = 16.5 B. p = .5; q = .5; X = 17.5 C. p = .25; q = .75; X = 16.5 D. p = .25; q = .75; X = 17.5
C. p = .25; q = .75; X = 16.5
Values of the __ are known and can be used to predict values of the ___. A. predictor variable; predictor variable B. criterion variable, predictor variable C. predictor variable; criterion variable D. criterion variable; criterion variable
C. predictor variable; criterion variable
A researcher measures the number of hours spent studying among students living on-campus and off-campus at a local college. In this study, location (on-campus, off-campus) is the ___ and hours spent studying is the ___. A. independent variable; dependent variable B. dependent variable; independent variable C. quasi-independent variable; dependent variable D. dependent variable; quasi-independent variable
C. quasi-independent variable; dependent variable
A questionnaire that assesses the degree to which people believe the world is a fair and just place has a mean of μ = 50. A researcher wonders if this belief is affected by exposure to information, suggesting that the world is not a fair and just place. To answer this research question, he conducts a study with 73 students and has them watch a series of videos where bad things happen to good people. After watching these videos, he gives them the questionnaire and finds that the average score after watching the videos was 48.1 with a standard deviation of 16.2. Which statistic would the researcher use to determine if watching the videos significantly reduced endorsement of the view that the world is fair and just? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
C. single sample t
A normal distribution with a mean of 0 and a standard deviation of 1 is called a: A. small normal distribution B. minimal normal distribution C. standard normal distribution D. centered normal distribution
C. standard normal distribution
The degrees of freedom for the related samples t-test are: A. the number of samples minus 1 B. the number of total scores minus 1 C. the number of difference scores minus 1 D. the number of groups minus 1
C. the number of difference scores minus 1
An 80% confidence interval for the population mean ranges from 14 to 22. Based on this information, ____. A. the sample mean is M = 14 B. the sample mean is M = 22 C. the sample mean is M = 18 D. none of the above choices is correct
C. the sample mean is M = 18
What value is placed in the denominator of the formula for estimated Cohen's d for the related samples t-test? A. estimated standard error B. population standard deviation C. the standard deviation of the difference scores D. the estimated standard error for the difference scores
C. the standard deviation of the difference scores
What is the estimation formula for the independent groups t-test? A. M ± z(σM) B. M ± t(sM) C. MD ± t(sD) D. (M1-M2) ± t(sM1-M2)
D. (M1-M2) ± t(sM1-M2)
For a normal distribution with µ = 50 and sigma = 10, what is the probability of randomly selecting a score greater than x = 56? A. 0.3446 B. 0.6554 C. 0.2743 D. 0.7257
D. 0.7257
A researcher selects a sample of 30 participants, randomly assigned to one of two groups. She conducts an independent groups t-test at a .05 level of significance. What is the smallest value that the test statistic could be for this test to result in a decision to reject the null hypothesis using a two-tailed test? A. 2.052 B. 2.042 C. 2.045 D. 2.048
D. 2.048
Compute the sample variance for the following data: 2, 4, 2, 5, 8, 19, 7, 12, 13, 9, 10, 13, 15, 19, 23, 3, 20, 18, 19, and 10. A. 6.430 B. 6.597 C. 41.348 D. 43.524
D. 43.524
For an exam with a mean of M = 74 and a standard deviation of s = 8, Mindy has a score of X = 80, Tosh's score corresponds to z = +1.50, and Sarah'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. Tosh, Mindy, Sarah B. Sarah, Tosh, Mindy C. Mindy, Tosh, Sarah D. Mindy, Sarah, Tosh
D. Mindy, Sarah, Tosh
What is the value of SS for the following set of scores? Scores: 5, 6, 1. A. 62 B. 13 C. 6 D. None of the other choices are correct.
D. None of the other choices are correct.
The mean is used to describe: A. data that are normally distributed B. data that are on an interval scale C. data that are on a ratio scale D. all of the above
D. all of the above
Which of the following statements about the normal distribution is true? A. the mean can equal any value B. the standard deviation can equal any positive value C. the total area under the normal curve is equal to 1.0 D. all of the above
D. all of the above
The median is: A. the preferred measure of central tendency when outliers are in a data set. B. the middle value in a distribution of 123 scores listed in numerical order. C. at the 50th percentile of of a cumulative percent distribution. D. all of the above.
D. all of the above.
An interval scale A. has no true zero B. is distributed on an equidistant scale C. is the most informative scale of measurement D. both a and b
D. both a (has no true zero) and b (is distributed on an equidistant scale)
A researcher measures the following correlation between the amount of fat consumed in a diet and general health: r = -0.62. Which of the following gives an appropriate description of the relationship between these two factors? A. Increased amount of fat in diet was negatively associated with general health, such that people who consumed more fat in their diet had lower general health. B. About 38%, of the variability in general health can be explained by the amount fat consumed in a diet. C. Increasing the amount of fat consumed in a diet leads to a decline in general health. D. both a and b
D. both a and b
A method for testing a claim or hypothesis about a parameter in a population, using data measured in a sample, is called: A. the central limit theorem B. hypothesis testing C. null hypothesis significance testing (NHST) or "significance testing" for short D. both b and c
D. both b and c
The denominator for sample variance is ___; the denominator for population variance is ___. A. N; n-1 B. n-1; N C. df; N D. both b and c
D. both b and c
For a population with a mean of 100, what is the z-score corresponding to a score that is located 10 points below the mean? A. +1 B. -1 C. -10 D. cannot answer without knowing the standard deviation
D. cannot answer without knowing the standard deviation
A researcher uses an analysis of variance to test for mean differences among three treatment conditions using a sample of n = 8 different participants in each treatment (between subjects design). What degrees of freedom would the F-ratio from this analysis have? A. df = 23 B. df = 2, 23 C. df = 3, 21 D. df = 2, 21
D. df = 2, 21
A population of scores has a mean of 50 and a standard deviation of 5. If every score in the population is multiplied by 3, then what are the new values for the mean and standard deviation? A. mean = 50 and standard deviation = 5 B. mean = 50 and standard deviation = 15 C. mean = 150 and standard deviation = 5 D. mean = 150 and standard deviation = 15
D. mean = 150 and standard deviation = 15
Which of the following is reported only with a related samples t-test and not for any other type of t-test A. the test statistic B. the p value C. the degrees of freedom D. none of the above; the same information is reported for all t-tests
D. none of the above; the same information is reported for all t-tests
A non-normal distribution has a mean equal to 3.4. What is the probability of a score above the mean? A. 0 B. 0.5 C. 1.0 D. not enough information to determine
D. not enough information to determine
A teacher of an art appreciation course wants to know if his course actually results in greater appreciation for the arts. On the first day of class, the teacher asks students to complete an art appreciation survey that assesses attitudes toward a variety of forms of art (e.g., painting, theater, sculpture). Responses on the survey range between 1 = strongly disagree to 5 = strongly agree. The same survey was given on the last day of class. The teacher analyzes the survey data and finds that scores were significantly higher on the last day of class than on the first day of class. Which statistic should this researcher use to determine if students' art appreciation scores were higher after the class than before the class? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
D. related samples t
The ___ is the square root of the ___. A. range; interquartile range B. mean; median C. variance; standard deviation D. standard deviation; variance
D. standard deviation; variance
What value is placed in the denominator of the formula for estimated Cohen's d for the single sample t-test? A. the standard error B. the estimated standard error C. the population standard deviation D. the sample standard deviation
D. the sample standard deviation
The results from a 2-factor ANOVA show a significant main effect for factor A and a significant main effect for factor B. Based on this information, you can conclude that A. there must be a significant interaction B. there probably is a significant interaction C. the interaction cannot be significant D. you cannot make any conclusion about the significance of the interaction
D. you cannot make any conclusion about the significance of the interaction
For a normal distribution, what z-score value separates the lowest 10% of the scores from the rest of the distribution? A. z = 0.10 B. z = 0.90 C. z = 1.28 D. z = -1.28
D. z = -1.28
Previous studies have shown that exposure to thin models is associated with lower body image among women. A researcher designs a study to determine if very young girls are similarly affected by thin images. Forty kindergarteners are randomly assigned to one of two groups. The first group plays with Barbie dolls for 30 minutes. The second group plays with a doll with proportions similar to the average American woman. After the 30-minute play period, the researcher measures each girl's body image using a graphic rating scale that is similar to a Likert scale. Which statistic should this researcher use to determine if the girls who played with Barbie dolls reported lower image than girls who played with dolls with proportions similar to the average American woman? A. z for a single score B. z for a sample mean C. single sample t D. related samples t E. independent samples t
E. independent samples t