BEHAVIORAL STATS FINAL REVIEW

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Assume the following for a paired-samples t test: N = 17, Mdifference = 467.72, s = 264.50. What is the effect size statistic?

1.77

This table reflects the fictional results of a study examining the impact of reinforcement on four groups of participants with different psychological disorders.he effect-size value, R2, for these data is:

0.37.

The table includes information for creating a regression equation to predict students' attitudes toward statistics from their attitudes toward Ed Sheeran and beer.Table: Coefficentsa Unstandardized CoefficientsStandardized Coefficients ModelBStd. ErrorBetatSig.Constant23.05430.331 1.1340.262attSheeran0.3092.2770.0160.1360.892attBeer0.4680.1020.5484.5880 a Dependent variable: Attitude toward statistics. (Table: Coefficients) What is the slope for predicting attitude toward statistics from attitude toward beer?

0.468

Gibson (1986) asked a sample of college students to complete a self-esteem scale on which the midpoint of the scale was the score 108. He found that the average self-esteem score for this sample was 135.2, well above the actual midpoint of the scale. Given that the standard deviation of self-esteem scores was 28.15, what would be the z score for a person whose self-esteem score was 104.28?

-1.10

If two sample means come from the exact same distribution, then the distribution of differences between means against which they will be compared should have a mean of:

Using the Bonferroni post hoc test, to make all possible comparisons between the means of four groups while keeping the overall p level at 0.05, what should the p level be for each comparison?

0.008

A researcher collects 25 data points that yield a mean of 8.164 and a standard deviation (based on N - 1) of 2.467. What is the standard error for the distribution of means?

0.493

Tej scored 60 on his final exam. His class's average score was 55, with a standard deviation of 5. How many standard deviations is Tej's score from the mean?

1 standard deviation above the mean

Six students from a psychology class reported the number of hours of television they watched per week. Here are their data: 12, 12, 11, 14, 13, 17. What is the mean number of hours of television watched per week for this sample of six students?

13.17

A 2 × 4 ANOVA will have 6 cells.

False

We would expect children's vocabularies to increase over time, with, say, 200 new words per year established as the standard. The null hypothesis for a paired-samples t test that assesses 150 children at age 5 and again at age 6 would assume an average mean difference of 200 word

True

When calculating a confidence interval for an independent-samples t test, you replace the population mean difference with the sample mean difference.

True

When the F statistic is more than the critical cutoff value, additional follow-up analyses are needed.

True

The testing service on your campus is conducting a study to determine how method of presentation (standard lecture versus computer presentation) and type of lecture (psychology, economics, statistics) relate to lecture comprehension. What kind of ANOVA should testing services use and what are the factors and/or levels?

Two-way ANOVA: Factor 1 is presentation, with two levels (standard versus computer), and factor 2 is lecture type, with three levels (psychology, economics, and statistics).

What would be the decision for the following paired-samples t test: t(28) = 1.81, p > 0.05?

fail to reject the null hypothesis

. You want to predict your score on the statistics final exam using your average quiz performance for the semester. Which statistical technique is best for this type of analysis?

simple linear regression

According to Cohen's conventions, an R2 of 0.01 is considered to be a(n) _____ effect size.

small

According to conventions, an ω2 of 0.02 is considered to be a(n) _____ effect size

small

For the data in the incomplete source table, what is the value of F for the second source, light condition? SourceSSdfMSFPaint color4.631.533 Light condition1.132 Paint × Light2.46 Within19.1480.398 Total27.459

1.420

This table and figure depict the average SAT scores for entering freshmen in the year 1995 at 36 North Carolina colleges.Table: North Carolina SAT 82592287011219901230130292610548458269568409238188676001030831935890879100584278075710027749159211071921915848915813 Figure: Histogram of SAT (Figure: Histogram of SAT) Based on the frequency distribution, approximately how many participants scored 1000 or above?

This table represents the fictional scores of a set of participants who rated their happiness on a scale from 1 to 7, with 1 indicating very unhappy and 7 indicating very happy.Table: Happiness X: 7,6,5,4,3,2,1 F: 3,5,11,9,3,1,2 (Table: Happiness) How many participants rated their happiness as 6 or higher?

In one psychology course, students reported studying an average of 8.62 hours a week, with a standard deviation of 4.24. The professor tells Anna she scored at the 46th percentile. How many hours does she study per week? (Round z score to two decimal places.)

8.20 hours

The use of probabilities based on prior beliefs is:

Bayesian statistics.

A researcher reports a paired-samples t test as follows: t(18) = 2.69, p < 0.05, d = 0.82. The value of the effect size measure here is:

0.82.

This table represents the fictional scores of a set of participants who rated their depression levels for the past two weeks on a scale from 1 to 4, 1 indicating No Depression and 4 indicating Depressed Most of the Time.Table: Depression XRating142232415361738491 (Table: Depression) The standard deviation in this data set is

1.15.

A distribution has a mean of 1.47 with a standard deviation of 0.34. A z score of -0.62 converts into a raw score of _____, whereas a z score of 0.62 converts into a raw score of _____.

1.26; 1.68

If the standard deviation for a population, as estimated from a sample, is s = 7.43, then the standard error for a sample size of N = 22 is sM =:

1.58.

This table represents the fictional scores of a set of participants who rated their optimism levels on a scale from 1 to 7, with 1 indicating very unoptimistic and 7 indicating very optimistic.Table: Optimism X Rating 1 1 2 7 3 6 4 7 5 7 6 6 7 5 (Table: Optimism) The standard deviation in this data set is

1.99.

Dana examined the GRE verbal scores of 10 first-year graduate students in her creative writing class to see the variability. Dana found the variance to be 135. What is the standard deviation?

11.619

. This histogram represents the distribution of the number of years of education completed by twins who attended the 16th Annual Twins Day Festival in Twinsburg, Ohio, in August of 1991.Figure: Years of Education (Figure: Years of Education) What is the mode of this distribution?

In the equation Ŷ = 125 + 4.2(X1) + 3.3(X2), what is the y intercept?

125

This table represents the fictional scores of a set of participants who rated their level of depression on a scale from 0 to 10, with 0 indicating no feelings of depression and 10 indicating very depressed.Table: Depression ScoreFrequency Percent 10 1 2.86 9 6 17.14 8 1 2.86 7 1 2.86 6 4 11.43 5 2 5.71 4 1 2.86 3 1 2.86 2 11 31.43 1 5 ? 0 2 5.71 (Table: Depression) What percent of participants rated their depression as 1?

14.29

This table represents the fictional scores of a set of participants who rated their level of depression on a scale from 0 to 10, with 0 indicating no feelings of depression and 10 indicating very depressed.Table: Depression ScoreFrequency Percent 10 1 2.86 9 6 17.14 8 1 2.86 7 1 2.86 6 4 11.43 5 2 5.71 4 1 2.86 3 1 2.86 2 11 31.43 1 5 ? 0 2 5.71 (Table: Depression) How many participants reported their level of depression at 5 or above?

Psychology students took longer to complete a quiz when music was playing in the background than when there was no background noise: t(17) = -6.23, p < 0.05. What is the sample size in this study?

The following dot plot displays daily hours of television viewing for a group of 25 students enrolled in a statistics class.Figure: Television Viewing Data Based on the data presented, what was the most commonly reported amount of daily television viewing?

5. Brunoni et al. (2006) investigated whether the combination of low-level electrical brain stimulation, transcranial direct current stimulation (tDCS), and sertraline, a commonly used SSRI antidepressant, would be effective in ameliorating depression in a group of clinically depressed individuals. The researchers randomly assigned participants to one of two medication conditions (placebo or sertraline) and to one of two brain electrical stimulation conditions (sham tDCS or active tDCS). How should the ANOVA used to analyze the data be labeled?

2 × 2 between-groups ANOVA

3. The campus testing service is conducting a study to determine the relation between method of presentation (standard lecture versus computer presentation) and type of lecture (psychology, economics, or statistics) to lecture comprehension. How would we describe the design?

2 × 3 between-groups ANOVA

A psychopathology researcher compares depression levels of individuals residing in five different climate regions. She collects data from 15 randomly selected people in each region. If she compares her groups using a between-groups, one-way ANOVA at a p level of 0.05, the critical value for her F statistic would be:

2.50

For the following data, what is the standard error of the difference scores? Before After

2.78

The results of an independent-samples t test were t(18) = 4.42, p < 0.05. In this example, the sample size is:

20.

Susan is figuring the regression line for some data but needs help in first figuring the predicted value of Y. She knows that the slope is 2 and the intercept is 7. What is the predicted Y value for an X score of 7?

Which set of scores has the least amount of variability?

22, 26, 21, 23

Here is a set of data: 30, 55, 27, 42, 39, 45, 38, 42. What is the range?

3.00

This table reflects the fictional results of a study examining the impact of reinforcement on four groups of participants with different psychological disorders.Table: Between-Groups Source TableSourceSSdfMSBetween36.95312.32Within63.20163.95Total100.1519 The F value for these data is:

3.12.

Six students from an economics class reported the number of hours of television they watch per week. Here are their data: 18, 12, 15, 14, 13, 16. The variance of the number of hours of television watched per week for this sample of six students is:

3.89.

Brunoni et al. (2006) investigated whether the combination of low-level electrical brain stimulation, transcranial direct current stimulation (tDCS), and sertraline, a commonly used SSRI antidepressant, would be effective in ameliorating depression in a group of clinically depressed individuals. The researchers randomly assigned participants to one of two medication conditions (placebo or sertraline) and to one of two brain electrical stimulation conditions (sham tDCS or active tDCS). How many cells does this study have?

This table represents the fictional ages of a set of participants who participated in a research study.Table: Age XAge134242340438542639718844933 (Table: Age) The variance in this data set is:

55.33.

. Roediger and Karpicke (2006) investigated whether the test-enhanced learning effect (the demonstration that repeated testing improves memory for material) was due merely to repeated exposure to material. They randomly assigned participants to one of two study conditions (study-study or study-test) and to one of three retention interval conditions (final test at a delay of 5 minutes, 2 days, or 1 week). The dependent variable was the proportion of idea units recalled from an encyclopedia passage. How many cells does this study have?

Fifteen college freshmen were asked to record the number of alcoholic drinks they typically consume in a week. Here are their data: 1, 4, 6, 0, 1, 9, 0, 6, 3, 6, 8, 5, 4, 7, 2. What is the mode of this distribution?

Lucas tosses a quarter 4 times and 3 times it comes up heads. The percentage of heads is:

75%.

Why does random assignment help control for confounding variables?

By randomly assigning people to groups, individual differences that may influence the dependent variable are randomly distributed throughout the conditions, rather than being systematically related to the independent variable.

Penina knows the z score for her research hypothesis is -2.05, and her critical values are -1.96 and 1.96 for a p value of 0.05. What should she conclude about her hypothesis given these statistics

She should reject the null hypothesis and report the direction of the effect because the score is in a critical region (below -1.96)

Little John, at the age of 8, is one of the tallest kids in his class, while his older brother Robin, at the age of 11, is one of the shortest kids in his class. Which statement would be true if their heights were converted to z scores?

Robin's would have a negative z score and John would have a positive z score

Based on research with her patients, Dr. Colburn knows that the correlation coefficient between scores on an anxiety scale and comfort at a social gathering is -0.35. If the critical value for r is 0.349, what should she conclude?

Scores on the anxiety scale are significantly related to feelings of comfort in a social gathering

3. Otis thinks some college students spend more money during the semester than others, and that this difference is related to the students' majors. He wants to compare the total amount of money spent at the end of one semester by 48 American college students who major in psychology to that spent by chemistry or English majors. What is the second step Otis should follow for testing his hypothesis?

State the null hypothesis as "College students majoring in psychology, chemistry, or English spend about the same amount of money during one semester, on average." State the research hypothesis as "College students majoring in psychology, chemistry, or English do not spend the same amount of money during one semester, on average."

After a researcher _____ the null hypothesis, the researcher should conduct a(n) _____ to determine which means are statistically significantly different from each other.

rejects; post hoc test

A researcher conducts a single-sample t test and finds statistical significance at the 0.01 level. The effect size is then calculated and found to be 0.05. What might be concluded about the findings?

The findings are statistically significant, but the effect size indicates that they may not be practically significant. A very large sample may have been studied, driving up the test statistic value

The median household income in Albemarle County, Virginia, for the year 2016 was $70,342. If the mean and mode are also computed, which statement could NOT be true?

The majority of households had incomes above the median.

What is one important reason for looking at visual descriptions of the data, such as frequency tables and histograms?

The patterns revealed in the data may lead to more specific research questions.

A marketing manager for a major department store wants to know how much time people tend to spend in the store so that the audio advertisements will replay on a timed loop, allowing every customer a chance to hear each unique message. What information is this marketing specialist seeking?

central tendency

A group of rats ran faster after receiving a steroid drug supplement compared to a group of rats that received no steroid drug supplement. Which type of statistical test should be used to report these results?

independent-samples t test

In a(n) _____, each participant is assigned to only one group so as to compare mean differences in a between-groups design.

independent-samples t test

Researchers were interested in whether mindfulness meditation training decreases the number of headaches a person experiences. They randomly assigned 28 participants to a control group or a mindfulness training group, and noted the change in number of headaches each group reported from the week before training to the week after training. Which statistical analysis should be performed to answer the researchers' question?

independent-samples t test

In a(n) _____ t test, the samples of participants are from different groups, while in the _____ t test, participants are from the same group.

independent-samples; paired-samples

When data are based on a nominal scale of measurement, what measure of central tendency should be used

mode

As the amount of overlap decreases among sample distributions, the:

more confident we are that the samples represent true differences in the population

The confidence interval provides _____ the hypothesis test.

more information than

. A researcher wants to be able to predict first-semester grade point average with as much accuracy as possible, so she would like to use both high school grade point average and SAT score as predictor variables. Which technique would be most appropriate to make this prediction?

multiple regression

As the number of classes a student attends increases, the number of errors made on the exam decreases. This is an example of what type of correlation?

negative

Nzinga wants to graph the number of hours of physical activity of a specific group of children over time, following them from the ages of 3 to 17 years. What would be the BEST type of graph for these longitudinal data?

time plot

The following source table depicts the results of a fictional study investigating whether the number of hours of sleep a person gets varies with gender (male, female) and with the number of cups of coffee consumed in a day. Equal numbers of men and women were randomly assigned to drink 1, 2, or 3 cups of coffee during the course of a day and then record the number of hours they slept that night.Table: Coffee and Sleep SourceSSdfMSFGender0.3810.380.33Cups of coffee75.38237.6932.76Gender × Cups3.6621.831.59Within34.51301.15 Total113.9335 (Table: Coffee and Sleep) For the data in the source table, what is the size of the effect for gender?

too small to be of interest

A nutritional researcher was interested in whether the size of breakfast could decrease overall food consumptions throughout the rest of the day. He creates two breakfast groups, a 350 calorie breakfast and a 750 calorie breakfast, assigns eight participants to each group, and tracks their total calories eaten in one day. Because of the detailed needed attention to accurately interview participants about their eating, he works with the high-calorie group and has his assistant interview the low-calorie group. What is the depended variable in this study?

total calories consumed

What needs to be known to determine the critical values for an independent-samples t test?

total degrees of freedom

. Data from the World Health Organization in 2013 were used to predict the life expectancy for men in a country from the life expectancy of women in the same country. The resulting regression equation was Ŷ = 3.73 + 0.88(X). This regression equation implies that:

when a woman's life expectancy increases by 1 year, a man's life expectancy increases by 0.88 of a year.

In a reanalysis of published studies, Twenge and Im (2007) found that during 1958-2001, the need for social approval of people in the United States was negatively correlated with the U.S. divorce rate during the same period (the correlation coefficient was -0.38). This correlation means that:

when the need for social approval was high, divorce rates were low.

A major limitation of the range as a measure of variability is that it:

will exaggerate the variability if there are outliers in the data set

The independent-samples t test is considered a between-groups design

True

The paired-samples t test allows you to assess how performance differs for one group of people over time.

True

The range is more susceptible to the influence of outliers than other measures of variability.

True

What is the correct formula for calculating degrees of freedom for an independent-samples t test?

dftotal = dfX + dfY

To calculate a confidence interval for an independent-samples t test, we use the:

difference between means.

. If between-groups variance is much larger than within-groups variance, we infer that the sample means are _____ one another, and we _____ the null hypothesis.

different from; reject

Dr. Simon wanted to know if IQ scores differed between male and female participants in his study. He gave 26 participants an IQ test and then examined IQ scores for gender differences. He hypothesized that there would be a statistically significant gender difference in IQ scores. Contrary to Dr. Simon's hypothesis, there were no differences in IQ scores between men and women in his study. What is the independent variable in this study?

gender

. For the data in the source table, calculate the effect size R2.SourceSSdfMSFBetween-groups10.125.05 Within-groups17.6121.47 Total27.714

0.36

Assume the following for a paired-samples t test: N = 15, Mdifference = 615.67, s = 628.50. What is the t statistic?

3.79

_____ is affected by outliers because it takes the actual value of each data point into consideration.

Mean

_____ is a weighted average of the two estimates of _____.

Pooled variance; variance

. _____ allow one to connect points on a map with data points located in space, such as homes for sale.

Geographic information systems (GIS)

In an independent-samples t test, how is the null hypothesis written in symbols?

H0: µ1 = µ2

In an independent-samples t test, how is the research hypothesis written in symbols?

H1: µ1 = µ2

0.10

This table reflects the fictional results of a study examining the impact of reinforcement on four groups of participants with different psychological disorders.Table: Between-Groups Source Table Source SS df MS Between 36.95 3 12.32 Within 63.20 16 3.95 Total 100.15 19 The effect-size value, ω2, for these data is:

0.24

For the data in the source table, calculate the effect size ω2. SourceSSdfMSFBetween-groups10.125.05 Within-groups17.6121.47 Total27.714

0.25

The correlation between the number of ounces of candy a child consumes weekly and the number of cavities the child has at the age 13 years is 0.74. If a child has a z score of -0.82 on the variable "candy consumed," the z score on the variable "number of cavities" would be predicted to be:

-0.61

A single-sample t test is conducted on a sample of 25 people who were selected from a large population estimated at 2500 people. The critical cutoffs for a two-tailed test at a p level of 0.05 would be:

-2.064 and 2.064

The critical cutoffs for a two-tailed Tukey HSD test comparing three group means with 14 within-groups degrees of freedom are:

-3.70 and 3.70

A statistics professor wants to determine whether class attendance can predict students' grades on their final exam. For his class of 16 students, he finds that the proportion reduction in error is 0.36. What would the adjusted r2 be for this data set?

0.31

Forys and Dahlquist (2007) investigated the effects of coping style and cognitive strategy on dealing with pain. Participants were first classified as having a monitoring or avoiding coping style. Participants were then randomly assigned to one of two cognitive strategy conditions, distraction or sensation monitoring. Participants were next instructed to use the cognitive strategy while submerging their hand in ice water. The researchers measured pain tolerance as the number of seconds that participants were able to keep their hand in the ice water. How many cells does this study have?

Fifteen college freshmen were asked to record the number of alcoholic drinks that they typically consume in a week. Here are their data: 1, 4, 6, 0, 1, 9, 0, 6, 3, 6, 8, 5, 4, 7, 2. What is the median number of alcoholic drinks consumed per week?

4.0

In the equation Ŷ = 78 + 4.10(X1) + 7.60(X2), what is (are) the slope(s)?

4.10 and 7.60

The following source table depicts the results of a fictional study investigating whether the number of hours of sleep a person gets varies with gender (male, female) and with the number of cups of coffee consumed in a day. Equal numbers of men and women were randomly assigned to drink 1, 2, or 3 cups of coffee during the course of a day and then record the number of hours they slept that night.Table: Coffee and Sleep SourceSSdfMSFGender0.3810.380.33Cups of coffee75.38237.6932.76Gender × Cups3.6621.831.59Within34.51301.15 Total113.9335 (Table: Coffee and Sleep) Using a p level of 0.05, the critical value for the main effect of gender is _____, and the critical value for the main effect of cups of coffee is _____.

4.17; 3.32

A standard deviation is equal to 4.50. This number means that the numbers in the sample deviate, on the average

4.50 units from the mean

A scientist analyzed the results of his data and calculated the standard deviation of scores at 6.4. What is the variance?

40.96

This table represents the fictional ages of a set of participants who participated in a research study.Table: Age XAge134242340438542639718844933 (Table: Age) The modal age (or mode) in this data set is:

42.00.

Children are regularly assessed for their height and weight compared to national data provided by the Centers for Disease Control. Arjan is somewhat short for his age, and his mother notices on his medical chart that it says Height: z = -1.64. What does this tell Arjan's mother about his height?

5.05 percent of children are shorter than Arjan

800-899

A graduate business class receives these grades on the final exam: 97, 75, 82, 87, 90, 72, 88, 88, 80, 93. What is the median test score?

87.5

The mean for the population is 82 with a standard deviation of 6. Given a z score of 1.45, what is the raw score?

90.70

A p level of 0.05 corresponds to a confidence interval of _____%.

Study Description: Tail WaggingA New York Timesarticle published on April 24, 2007, reported the research of Dr. Giorgio Vallortigara, a neuroscientist at the University of Trieste, Italy, and his two colleagues. The researchers asked whether a dog wags its tail in a preferred direction in response to positive stimuli and in another direction in response to negative stimuli. To answer their question, they recruited 30 dogs that were family pets. Filming each dog from above, they allowed it to view (through a slat in its cage) three positive stimuli separately, in order of descending positivity: its owner, an unfamiliar human, and a cat. All the dogs responded by wagging their tails to the right. But when the dogs were presented with an unfamiliar, aggressive dog, a negative stimulus, all dogs wagged their tails to the left.

A dog's tail will wag differently in response to positive stimuli than to negative stimuli

In which situation would it NOT be appropriate for a researcher to use a one-way ANOVA in analyzing the data?

A researcher classifies a group of college students on the basis of their political leanings as liberal, conservative, libertarian, or green.

In which situation would a researcher need to use a within-groups ANOVA to analyze the data?

A researcher is interested in a longitudinal study that follows a group of kindergarten children through high school and assesses their body mass index at four time points

In which situation would a researcher need to use a between-groups ANOVA to analyze the data?

A researcher is interested in the effects of distraction on driving performance and randomly assigns participants to one of three distraction groups.

Rita wants to compare young children's reading test scores across three experimental conditions (different styles of instruction, such as phonics and reading recovery) and one control group (no instruction). What type of test should she use?

ANOVA

The correlation coefficient between two variables, height and IQ score, is zero. What does this statement mean?

As the value of one variable changes, the other is not necessarily affected.

A researcher performs a meta-analysis and finds that the mean d = 0.45, and the 95% confidence interval around this mean is [0.34, 0.56]. What can the researcher conclude?

Averaging across all of the literature, there is a medium effect, and this effect is statistically significant.

A researcher performs a meta-analysis and finds that the mean d = 0.11, and the 95% confidence interval around this mean is [-0.04, 0.26]. What could the researcher conclude?

Averaging across all of the literature, there really is no effect.

According to the Federal Reserve, the average credit card interest rate in 2017 was 12.54% (averaged across all credit card accounts at all reporting banks). A researcher wanted to know if college students at her institution have different interest rates compared to this national statistic. If conducting a single-sample t test, which statement would serve as her research hypothesis?

College students have different interest rates on average compared to the nation

Which of these is an example of randomly assigning participants to conditions in a study?

Every time a participant shows up for his study, Samuel flips a coin to determine which condition to put the participant in. He predetermined that heads is the control group and tails is the experimental group.

An F statistic calculated on 2 and 38 degrees of freedom equals 2.90. Which decision should be made about a hypothesis tested at the p = 0.05 level?

Fail to reject the null hypothesis and conclude there are no significant differences among the groups.

A paired-samples t test results in the following statistic: t(16) = 2.01. Using this test result, what decision should be made about a two-tailed hypothesis test at p = 0.05?

Fail to reject the null hypothesis because the test statistic does not exceed the critical cutoff.

A correlation coefficient higher than 0.05 is extremely unusual in behavioral science research.

False

A correlation coefficient of 0.05 is considered a large effect by Cohen (1988).

False

A sample of 21 with a standard deviation of 82.41 results in a standard error calculated as 18.42.

False

An interaction is more likely to occur in a two-way ANOVA when at least one of the main effects is significant.

False

Correlation coefficient and proportionate reduction in error are inversely related; that is, as the correlation coefficient increases, proportion reduction in error decreases.

False

If two variables are negatively correlated, they cannot be causally related.

False

It is easier to distort and lie with the median than with the mean

False

Some researchers believe hypothesis testing should completely replace Bayesian statistics.

False

When comparing two z scores to assess performance on an exam, one would conclude that a student with a z of -2.3 outperformed someone with a z of 1.7 because the first score is more extreme

False

When reporting the test results for an independent-samples t test, N is reported rather than degrees of freedom

False

When the F statistic is less than the critical cutoff value, additional follow-up analyses are needed.

False

An education researcher is worried that performance on a statistics aptitude test will improve simply because of repeated exposure to the instrument, which will cloud his ability to assess the impact of two unique educational interventions he wants to study (Program A and Program B). Which of these design options includes counterbalancing?

He could vary the order of the educational interventions such that half of the participants experience Program A first and the other half experience Program B first

Lou examined tolerance to four different psychoactive drugs among different groups of rats. He found a significant difference between groups and wishes to report an effect size for his study. Lou asks for your advice on whether to report R2 or ω2 for his data. What would you advise?

He should report ω2, as it is a less biased measure of effect size than R2.

Carli visually inspects her data before analyzing it, only to find that the populations that she sampled appear to have very different variances although her sample sizes are equal. Which assumption of ANOVA has she violated, and what should she do?

Homoscedasticity; she should proceed as long as the largest variance is not greater than two times the smallest variance and report it with her statistic

Justin is examining the effectiveness of using scare tactics to manipulate the behaviors of 54 people living in different regions of the same island, categorized as the beach, the valley, and the mountains. What is the first step Justin should follow for hypothesis testing?

Identify population 1 as all beach inhabitants on the island, population 2 as all valley inhabitants on the island, and population 3 as all mountain inhabitants on the island. He should also use an F distribution with a one-way between-groups ANOVA.

Which of these is NOT a benefit of performing a meta-analysis?

It increases the chances of misinterpreting data by analyzing half of the studies

If the standard deviation of some data is 6.19, what is the range?

It is impossible to determine the range based on the information provided

Jillian wants to test how different levels of verbal ability and math ability influence a measure of reading comprehension and a measure of graph interpretation. She is concerned that IQ may confound the results because it is likely to have an effect, too. What test should she use to account for this third variable?

MANCOVA

Myra notices that every time she wears dresses to work, she has a very productive day and finishes all her projects on time. When she doesn't wear dresses, she struggles to get everything done. She concludes that wearing dresses is the cause for her successful days at work and buys more dresses. Is she correct?

No; she cannot make causal claims from correlations.

The following table reflects the results of a study by Roediger and Karpicke (2006). The authors investigated whether the test-enhanced learning effect (the demonstration that repeated testing improves memory for material) was due merely to repeated exposure to the material. They randomly assigned participants to one of two study conditions (study-study or study-test) and to one of three retention interval conditions (final test at a delay of 5 minutes, 2 days, or 1 week). The dependent variable was the proportion of idea units recalled from an encyclopedia passage.Table: Test-Enhanced Learning 5 minutes2 days1 weekMeanStudy-study0.80.550.420.59Study-test0.750.70.550.67Mean0.780.630.49 (Table: Test-Enhanced Learning) The cells of this study reflect an interaction. Which statement best describes the interaction?

People in the study-test condition performed more poorly on the 5-minute recall test than did those in the study-study condition, but at longer retention intervals (2 days and 1 week); those in the study-test condition performed better than did those in the study-study condition.

The following figure reflects the results of a study by Forys and Dahlquist (2007) investigating the effects of coping style and cognitive strategy on dealing with pain. Participants were first classified as having a monitoring or avoiding coping style. They were then randomly assigned to one of two cognitive strategy conditions, distraction or sensation monitoring. Participants were next instructed to use the cognitive strategy while submerging their hand in ice water. The researchers measured pain tolerance as the number of seconds that participants were able to keep their hand in the ice water.Figure: Strategies for Dealing with Pain (Figure: Strategies for Dealing with Pain) The figure reflects a main effect of coping style. Which statement best describes the main effect?

People with an avoiding coping style were able to keep their hand in the ice water for longer than people with a monitoring coping style.

The following table reflects the results of a study by Forys and Dahlquist (2007) investigating the effects of coping style and cognitive strategy on dealing with pain. Participants were first classified as having a monitoring or avoiding coping style. They were then randomly assigned to one of two cognitive strategy conditions, distraction or sensation monitoring. Participants were then instructed to use the cognitive strategy while submerging their hand in ice water. The researchers measured pain tolerance as the number of seconds that participants were able to keep their hand in the ice water.Table: Coping with Pain DistractionSensation MonitoringMeanMonitoring84.593.388.9Avoiding136.885.6111.2Mean110.789.5 (Table: Coping with Pain) The cells of this study reflect a main effect of coping style. Which statement best describes the main effect?

People with an avoiding coping style were able to keep their hand in the ice water for longer than people with a monitoring coping style.

A mood researcher investigates whether chocolate affects emotions. He recruits college students to take a mood inventory, ingest 0.25 pound of chocolate, and then complete the mood inventory again. Given the confidence interval [1.37, 4.21], what decision about the hypothesis should the researcher make?

Reject the null hypothesis and conclude that chocolate affected mood because 0, or no effect, does not fall within the confidence interval

A state transportation department is determining the safety of interstate roadways based on the age of drivers and number of traffic accidents. The department calculates a Pearson correlation coefficient of 0.305. If the critical value for r = 0.330, what could it conclude?

The age of drivers is not significantly related to the number of traffic accidents.

The following figure reflects the results of a study by Forys and Dahlquist (2007) investigating the effects of coping style and cognitive strategy on dealing with pain. Participants were first classified as having a monitoring or avoiding coping style. They were then randomly assigned to one of two cognitive strategy conditions, distraction or sensation monitoring. Participants were next instructed to use the cognitive strategy while submerging their hand in ice water. The researchers measured pain tolerance as the number of seconds that participants were able to keep their hand in the ice water.Figure: Strategies for Dealing with Pain (Figure: Strategies for Dealing with Pain) The figure reflects an interaction between coping style and cognitive strategy. Which statement best describes the interaction?

The effect of cognitive strategy depended on the coping style of the participant. People with an avoiding coping style kept their hand in the ice water longer when using a distraction strategy, but those with a monitoring coping style kept their hand in the ice water longer when using a sensation-monitoring strategy.

The owners of the Syfy channel are interested in whether watching the Syfy channel causes people to become "geeky," and if so, whether any such effects depend on a person's gender. They hire a researcher to design and carry out the appropriate study. The researcher randomly assigns an equal number of men and women to watch 0, 3, 5, or 9 hours of the Syfy channel each week for 6 weeks. What is the null hypothesis for the interaction effect?

The effect of hours of the Syfy channel watched is not dependent on gender

The following figure reflects the results of a study by Brunoni et al. (2006) that investigated whether the combination of low-level electrical brain stimulation, transcranial direct current stimulation (tDCS), and sertraline, a commonly used SSRI antidepressant, would be effective in ameliorating depression in a group of clinically depressed individuals. The researchers randomly assigned participants to one of two medication conditions (placebo or sertraline) and to one of two brain electrical stimulation conditions (sham tDCS or active tDCS). Participants' levels of depression was assessed using the Montgomery-Asberg Depression Rating Scale (MADRS) after six weeks of treatment.Figure: Brain Stimulation and Medication (Figure: Brain Stimulation and Medication) The figure reflects an interaction between medication and electrical stimulation. Which statement best describes the interaction?

The reduction in depression scores as a result of active tDCS was greater for those individuals who received active medication as compared to those individuals who received placebo.

When there is uncertainty about the parameters of a population of interest, a t distribution is used instead of a z distribution. Is the t distribution wider or thinner than the z distribution and why?

The t distribution is wider because we are less certain of the findings compared to the z distribution.

A Tukey HSD is computed to compare two groups following an ANOVA that compared five groups. The within-groups degrees of freedom for the test are 15, and the computed HSD value is 5.24. What could we conclude about this analysis if we evaluated it at a p level of 0.05?

The test statistic is significant, revealing a statistical difference between the two groups.

A researcher is interested in the number of days spent unemployed and feelings of depression related to work. She recruits 82 unemployed professionals randomly from a list provided by her community unemployment office. She computes a correlation of -0.38. What decision would this researcher make for a two-tailed hypothesis test at a p level of 0.05?

The test statistic is significant, so she rejects the null hypothesis and concludes that the number of days spent unemployed is negatively correlated with feelings of depression

If an F statistic is negative, which of these statements is true?

There has been a calculation error.

An experimenter rejects the null hypothesis after using an F table to determine the significance value. What can be concluded?

There is a difference between means that is larger than we would predict by chance

An interval estimate offers an advantage over a point estimate because it estimates the population parameter using a range of values rather than a single number.

True

Study Description: Texting During ClassDietz and Henrich (2014) were interested in the impact of texting on student learning. A group of 99 college students were randomly assigned to text (N = 50) or not text (N= 49) during a pre-recorded psychology lecture. At the end of the 20-minute lecture, students answered a 17 question quiz about the material that had just been presented. On average, the researchers found that students who texted during the lecture answered fewer quiz questions correctly as compared to students who hadn't texted during the lecture. (Study Description: Texting During Class) Which statement is the null hypothesis for this study?

There will be no difference in the quiz grades of the two groups after both groups listen to the 20-minute lecture.

In 2000, Bartels and Zeki conducted a study in which they hypothesized that there may be special pathways in the brain that support the feeling of romantic love. To test their hypothesis they recruited volunteers who reported themselves to be "truly, deeply, and madly in love." They then used brain imaging methods to determine which areas of the volunteers' brains were active when looking at pictures of their loved one. How did these researchers operationally define romantic love?

They used self-reports of volunteers who claimed to be "truly, deeply, and madly in love."

The following figure reflects the results of a study by Forys and Dahlquist (2007) investigating the effects of coping style and cognitive strategy on dealing with pain. Participants were first classified as having a monitoring or avoiding coping style. They were then randomly assigned to one of two cognitive strategy conditions, distraction or sensation monitoring. Participants were next instructed to use the cognitive strategy while submerging their hand in ice water. The researchers measured pain tolerance as the number of seconds that participants were able to keep their hand in the ice water.Figure: Strategies for Dealing with Pain (Figure: Strategies for Dealing with Pain) The figure reflects an interaction. Is this a quantitative or qualitative interaction? Why?

This is a qualitative interaction because the effect of coping style reverses depending on the cognitive strategy employed.

The following figure reflects the results of a study by Brunoni et al. (2006) that investigated whether the combination of low-level electrical brain stimulation, transcranial direct current stimulation (tDCS), and sertraline, a commonly used SSRI antidepressant, would be effective in ameliorating depression in a group of clinically depressed individuals. The researchers randomly assigned participants to one of two medication conditions (placebo or sertraline) and to one of two brain electrical stimulation conditions (sham tDCS or active tDCS). Participants' levels of depression was assessed using the Montgomery-Asberg Depression Rating Scale (MADRS) after six weeks of treatment.Figure: Brain Stimulation and Medication (Figure: Brain Stimulation and Medication) The figure reflects an interaction. Is this a quantitative or qualitative interaction? Why?

This is a quantitative interaction because the effect of electrical brain stimulation does not reverse depending on the type of medication used

A sample of 21 with a standard deviation of 82.41 results in a standard error calculated as 17.98.

True

Replication can help determine the circumstances in which a finding holds true or not.

True

Why is it necessary to use the pooled variance when conducting an independent-samples t test?

We are working with two samples, and an estimate of spread based on two samples is likely to be more accurate than an estimate of spread based on a single sample

According to the video game industry's statistics, the average gamer is 32 years old. Imagine the standard deviation for age is 7.7 years. Yahzid collected data on video gaming among people with new tablets or iPads to see if the mean age of that group is older or younger. He finds an average age of 36.5 years based on a sample size of 57. His 95% confidence interval is:

[34.5, 38.5].

Milo insists that women are poorer drivers than men. To back up his claim he describes two incidents: one in which his girlfriend sideswiped a car and a second in which his mother failed to react in time to avoid hitting a squirrel on the highway. Milo's attention to this positive evidence for his belief reflects:

a confirmation bias

The following figure reflects the results of a study by Forys and Dahlquist (2007) investigating the effects of coping style and cognitive strategy on dealing with pain. Participants were first classified as having a monitoring or avoiding coping style. They were then randomly assigned to one of two cognitive strategy conditions, distraction or sensation monitoring. Participants were next instructed to use the cognitive strategy while submerging their hand in ice water. The researchers measured pain tolerance as the number of seconds that participants were able to keep their hand in the ice water.Figure: Strategies for Dealing with Pain (Figure: Strategies for Dealing with Pain) Based on the figure, which effects appear to be present?

a main effect of coping style, a main effect of cognitive strategy, and an interaction between coping style and cognitive strategy

The following figure reflects the results of a study by Brunoni et al. (2006) that investigated whether the combination of low-level electrical brain stimulation, transcranial direct current stimulation (tDCS), and sertraline, a commonly used SSRI antidepressant, would be effective in ameliorating depression in a group of clinically depressed individuals. The researchers randomly assigned participants to one of two medication conditions (placebo or sertraline) and to one of two brain electrical stimulation conditions (sham tDCS or active tDCS). Participants' levels of depression was assessed using the Montgomery-Asberg Depression Rating Scale (MADRS) after six weeks of treatment.Figure: Brain Stimulation and Medication (Figure: Brain Stimulation and Medication) Based on the figure, which effects appear to be present?

a main effect of medication, a main effect of electrical brain stimulation, and an interaction between medication and electrical brain stimulation

The following figure reflects the results of a study by Roediger and Karpicke (2006). The authors investigated whether the test-enhanced learning effect (the demonstration that repeated testing improves memory for material) was due merely to repeated exposure to the material. They randomly assigned participants to one of two study conditions (study-study or study-test) and to one of three retention interval conditions (final test at a delay of 5 minutes, 2 days, or 1 week). The dependent variable was the proportion of idea units recalled from an encyclopedia passage.Figure: Testing and Memory (Figure: Testing and Memory) Based on the cells of this study, which effects appear to be present?

a main effect of study condition, a main effect of retention interval, and an interaction between study condition and retention interval

The following source table depicts the results of a fictional study investigating whether the number of hours of sleep a person gets varies with gender (male, female) and with the number of cups of coffee consumed in a day. Equal numbers of men and women were randomly assigned to drink 1, 2, or 3 cups of coffee during the course of a day and then record the number of hours they slept that night.Table: Coffee and Sleep SourceSSdfMSFGender0.3810.380.33Cups of coffee75.38237.6932.76Gender × Cups3.6621.831.59Within34.51301.15 Total113.9335 (Table: Coffee and Sleep) Using a p level of 0.05, what are the significant effects?

a main effect of the number of cups of coffee and no other effects

Successful replication of research builds a case for the generalizability of findings. In order for replications to build that strong case, it is important that they occur in:

a new context or with samples that have different characteristics

Measures of central tendency and variability are calculated to describe the nature of charitable giving each year. These figures are computed for the "average" American citizen. In that case, the mean calculated would be taken as:

a population parameter.

Before conducting a power analysis, a researcher should know the desired:

alpha level.

According to the null hypothesis, the mean difference for the comparison distribution in a paired-samples t test is:

always 0.

This figure depicts data from the Schachter (1968) study on obesity and eating behavior.Figure: Taste Test (Figure: Taste Test) The type of graph depicted in this figure is a:

bar graph

In calculating pooled variance, why are adjustments made for sample size

because estimates from smaller samples tend to be less accurate than those from larger samples

As the correlation coefficient becomes stronger, proportionate reduction in error

becomes larger.

A psychological researcher wants to assess well-being among dog and cat owners. She administers a well-being assessment to 125 dog owners and 163 cat owners. What type of research design is being used?

between-groups

The t statistic is more _____ than the z statistic because the researcher is less likely to observe an extreme t statistic.

conservative

A placebo group is an example of a type of a(n) _____ group.

control

A researcher does not find support for his research hypothesis. He should then make which of these decisions?

fail to reject the null hypothesis

fail to reject; reject

If an analysis of variance includes both within-groups factors and between-groups factors, it is called a _____ ANOVA.

mixed-design

gender and hours of Syfy watched

This table shows tests scores for a cumulative final in a general education, social science course, such as introduction to psychology.Table: Test Scores IntervalFrequency90-992380-894170-797860-693650-591840-49730-391220-293 (Table: Test Scores) What kind of frequency distribution is this?

grouped frequency table

It was once believed that the intelligence of a person was related to their head size. If there is no actual association between these variables, this would be an example of a(n):

illusory correlation

At major research universities, the intense pressure to publish has led a few people to act desperately, creating fake data to impress their reviewers and colleagues. This faking may be demonstrated in the visual distortion of data in graphing. This is an example of a(n) _____ lie.

inaccurate values

The relation between the number of class sessions attended and the grade obtained on the final exam for students enrolled in a statistics course during the fall 2018 semester is shown in the figure.Figure: Attendance and Exam Grade (Figure: Attendance and Exam Grade) Based on the scatterplot, it appears that as the number of classes a student attends increases, the grade on the final exam:

increases.

To determine whether a chemical found in many common plastic items is toxic, researchers fed different amounts of the chemical (from 0 to 20 micrograms) to mice and later performed a blood test to determine the amount of toxins present in each mouse. To create a scatterplot of the data, which variable should be listed on the x-axis?

independent variable, which is the amount of the chemical given to the mice

This figure depicts the relation between the level of poverty, as measured by the proportion of students qualifying for free and reduced lunch, amongst students at 11 middle schools in a medium sized midwestern city and the 9th grade core grade point average (GPA) of the students from those 11 middle schools.Figure: Poverty and GPA (Figure: Poverty and GPA) From this graph, one knows with certainty that students from a middle school with a 30 percent poverty rate would have an average GPA of 3.0 in 9th grade. This statement is an example of a(n) _____ lie.

interpolation

When scientists call a hypothesis test conservative, they mean that it:

is difficult to reject the null hypothesis (i.e., the status quo).

According to conventions, an ω2 of 0.17 is considered to be a(n) _____ effect size.

large

An effect size of 0.21 for a two-way ANOVA is considered to be:

large

For a data set that has been skewed due to outliers, what measure of central tendency is most accurate and should be reported?

median

If you knew nothing about your data except that it is a scale variable, which measure of central tendency would be the "safest bet"?

median

According to Cohen's conventions, an R2 of 0.05 is considered to be a(n) _____ effect size

medium

A t statistic is _______ a z statistic, making it _______.

not as extreme as; more conservative

The results of t(22) = 1.78, p > 0.05 indicate that the _____ is plausible

null hypothesis

When reading your college textbooks, you may sometimes find errors in them. If you track the number of errors based on the edition of the textbook, you might find that 1st editions have more errors than 3rd, 5th, and 10th editions. What type of variables the edition of the text you are assessing?

ordinal

A psychologist is interested in whether working memory is influenced by sleep loss. The psychologist administers a measure of working memory to a group of subjects at 8 A.M. on day 1 of the study and then again at 8 A.M. on day 2 of the study, after keeping the subjects awake the entire night. Does sleep loss affect working memory? What statistical analysis should be performed to answer this question?

paired-samples t test

In which statistical test do you calculate a difference score for each individual, take the mean of the difference scores, and perform a test on them to compare two sample means?

paired-samples t test

A psychological study designed to assess the effects of disclosure of ingredients on the experience of taste, Lee, Frederick, and Ariely (2006) approached patrons at a local pub and asked them to taste and rate a new beer: the MIT Brew. Some participants were told about the secret ingredient in the beer (a few drops of balsamic vinegar) either before tasting (before condition) or after tasting but before rating (after condition). Other participants were not told anything regarding the secret ingredient (not told condition). Which aspect of this study is an operational definition of the dependent variable?

participants' responses on the taste rating scale

The hamilton depression rating scale (HDRS) is a scale intended to measure depression levels, with higher scores indicating higher levels of depression. If the HDRS is a valid measure of depression, we would expect that:

people who get higher scores on the HDRS would be more depressed than people who get lower scores.

In an independent-samples t test, the _____ is used rather than the _____

pooled variance; standard deviation

. The relation between the number of class sessions attended and the grade obtained on the final exam for students enrolled in a statistics course during the fall 2018 semester is shown in the figure.Figure: Attendance and Exam Grade (Figure: Attendance and Exam Grade) Based on the scatterplot, what is the relation between a student's class attendance and grade on the final exam?

positive

As the age of a male professor increases, his income increases. This is an example of what type of correlation?

positive

What would be the decision for a two-tailed paired-samples t test where the confidence interval was determined to be [-3.45, -0.91]?

reject the null hypothesis

Which statistic quantifies the improvement in ability to predict a person's score when using the regression line rather than the mean

proportionate reduction in error

There are three steps involved in creating the comparison distribution for the independent-samples t test, and those steps are repeated many times. Which of these is the sequence described in the text?

randomly select scores and calculate their mean as the group 1 mean, randomly select another group of scores and calculate their mean as the group 2 mean, and subtract the second mean from the first

Bar graphs are highly informative, but they can also be deceiving because what seems to be a significant difference in means may actually be a small difference. What part of the graph reveals whether a difference in means is exaggerated?

range of values on the y-axis

A psychologist was interested in measuring reaction time differences between men and women on a computerized task. What is the dependent variable?

reaction time

Every year it seems as though last season's baseball rookie of the year fails to live up to expectations for his sophomore season. What might explain this phenomenon?

regression to the mean

Numbers that describe samples are called:

statistics.

It becomes progressively easier to declare statistical significance as the _____ increases.

sample size

Two students recently took trigonometry class tests. The students are at different schools but wanted to compare their performance. The first student scored 80 on the test. Her class average was 85 with a standard deviation of 5. The second student scored 65. Her class average was 50 with a standard deviation of 10. Which student did better?

second student because she performed better relative to her class

Of the four types of population parameters used to describe any distribution, which parameter describes how far the observations scatter around the central value?

standard deviation

In an introductory psychology course, the average score on the first exam was 78 percent based on a sample of 146 students. This mean was calculated on the class grades to summarize overall performance. There are two other sections of the same class, but those students were not included in the calculation. The test average is a:

statistic.

The correlation coefficient is how one measures the _____ of a correlation.

strength

Which of these is NOT an appropriate tool for locating a specific point on a normal bell-shaped curve?

sum of squares

Which of these illustrates a statistically insignificant result for an independent-samples t test?

t(15) = 1.89, p > 0.05

Of the statistical results shown here, which would lead us to reject the null hypothesis?

t(15) = 2.23, p < 0.05

Which of the following reports of statistical results is in appropriate APA format?

t(27) = 3.5, p < 0.05

Because of the principle of _____, when sample sizes are at least 30, the distribution will most likely resemble a normal distribution.

the central limit theorem

This figure was created from 2018 U.S. News & World Report data on 4-year colleges and universities in the United States.Figure: Cost of Tuition (Figure: Cost of Tuition) The dependent variable in this study was:

the cost of tuition and fees

A researcher in I/O psychology investigates the impact of color and lighting on mood at work. She manipulates the paint used in offices, including the presentation of four different colors. She also manipulates lighting by using three different lighting conditions. The null hypothesis for the interaction in this study would be:

the effect of office color is not dependent on the type of lighting condition.

the individual conducting the interview

The statement "On average, older adults have the same response time as younger adults" is an example of:

the null hypothesis.

The statement "On average, older adults have a different response time than younger adults" is an example of:

the research hypothesis

If the points on a scatterplot are all far away from the regression line:

the standard error of the estimate is large

If the points on a scatterplot are all close to the regression line:

the standard error of the estimate is small.

In a table depicting the cells of a two-way ANOVA, the marginal means reflect:

the two main effects.

This figure was created from 2018 U.S. News & World Report data on 4-year colleges and universities in the United States.Figure: Cost of Tuition (Figure: Cost of Tuition) The independent variable in this study was:

the type of college

A dot plot offers an advantage over a histogram in that it shows the individual data points and can be easier to interpret.

true

The statement "It is hypothesized that depressed and anxious participants will differ on reaction time measures" best illustrates a:

two-tailed test.

Noah is looking at a histogram depicting students placed in various high schools. In this histogram, the x-axis most likely represents the _____ while the y-axis most likely represents the _____.

values of the variable "high school"; frequencies or number of students

An effect size of d = 0.05 would indicate a:

very small effect

Students who post responses on ratemyprofessor.com are what type of sample?

volunteer

An article from the New York Times, published on April 24, 2007, summarized research conducted by Dr. Vallortigara, a neuroscientist at the University of Trieste, Italy. In this study, Dr. Vallortigara assessed whether a dog's tail wags in a preferred direction in response to positive as opposed to negative stimuli. First Dr. Vallortigara recruited 30 dogs that were family pets. While filming a dog's tail from above, he allowed the dog to view (through a slot in its cage) its owner, an unfamiliar human, a cat, and an unfamiliar dominant dog. The study found that dogs' tails wagged to the right for the owner and to the left for the unfamiliar dominant dog. What type of research design did Dr. Vallortigara employ?

within-groups

in which type of research design does each participant experience all levels of the independent variable?

within-groups

Interested in the effects of different kinds of instruction on video game performance, Venera asks 36 college freshmen to each play one hour of Ratchet and Clank. Participants are randomly assigned to one of three instruction groups: (1) complete the tasks as quickly as possible, (2) conserve as much health as possible (i.e., play more carefully), or (3) find gold bolts (worth lots of money in equipment and ammunition). Obviously, even in a single instruction group, not all players will obtain the same final score. These differences in an instruction group reflect:

within-groups variance.

The paired-samples t test is an example of a _____ test, while the independent-samples t test is an example of a _____ test.

within-groups; between-groups

What kind of correlation would you expect to find between the results of two dice thrown simultaneously?

zero

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