Stats Unit 3

Given M1 = 12.50, M2 = 14.33, and s2pooled = 11.00, what is Cohen's d?

-0.55

If M = 100.00, μ = 115.00, and sM = 13.25, what is the value of t?

-1.13

Which of these values would result in failure to reject the null hypothesis for a two-tailed test?

-tcv < t < tcv

When establishing the critical value of t, what is the acceptable rate (expressed as a probability) of committing a Type I error?

.05

Dave collects data on the number of days people exercise each month. If the average of his sample is 15.13 days (s = 5.33), what is the effect size if Dave compares his sample with a population mean of 14 days?

0.21

Which of these values would be considered a medium effect size, using Cohen's d?

0.50

If an average student from a high school scored a 550 on the SAT and the national average is 500, what is d if s = 95?

0.53

If n1 = 5, s1 = 3, n2 = 10, and s2 = 4, what is the standard error of the difference?

2.04

Carmen compared the test performances of the students in her school to the average of schools in her state. Based on the data she collected, Carmen calculated t = 1.981. If alpha was set at .05 and she conducted a two-tailed test, what was Carmen's decision regarding the hypothesis?

Carmen rejected the null hypothesis.

What analysis is used to determine the effect size when calculating an independent-samples t test?

Cohen's d

Which of these describes how the t statistic is calculated?

First, the population mean is subtracted from the sample mean and then divided by the estimated standard error of the mean.

The critical value of t is best defined as the:

cut-off for determining whether or not to reject H0.

Tyler, Ashley, Austin, and Emily want to compare the number of hours that children in their local elementary school engage in physical activity with that of elementary school students in general. All things being equal, which researcher will have more difficulty rejecting H0?

Tyler, who collects data from 10 participants

Dani assesses the levels of secure attachment in elementary schoolchildren and high school students and calculates the mean scores of both samples (Melementary = 60.00, Mhigh school = 58.00). If s2pooled = 50.00, what is Cohen's d?

1.29

Two-sample t tests are used to:

compare the mean of one population to the mean of another population.

Dr. Shoals predicts that people who walk a mile in moderately high heels and very high heels will differ in their levels of reported back pain. Thirteen men and 14 women walk in 4-inch heels and 2.5-inch heels. He calculates the standard deviation of the difference scores and finds sD = 3.37. What is the standard error of the difference for difference scores?

0.65

Faith collects data on how many medications different groups of patients with cardiovascular disease take on a weekly basis. If she collects data from 15 patients with heart failure and 7 patients with blocked arteries and finds that the standard deviation for the heart failure group is 2.00 and the standard deviation is 1.00 for patients with blocked arteries, what is the standard error of the difference?

0.81

Given M1 = 9.00, M2 = 6.50, and sM1-M2 = 2.12, what is the value of t?

1.18

Erica assesses the number of visits that elementary schoolchildren make to the nurse's office. If students from School A make an average of 5.25 visits per year and students from School B make an average 3.75 visits per year, what is t if sM1-M2 = 1.23?

1.22

Cheryl wants to know the number of activities that children engage in based on their caregivers' parenting style. She collects data on 50 authoritative parents and 43 authoritarian parents. If the standard deviation for the authoritative parents is 6.00 and the standard deviation for authoritarian parents is 8.00, what is the standard error of the difference?

1.45

If a researcher collects data from 68 people, what would the critical value of t be if he conducted a one-tailed test with alpha equal to .05?

1.669

Consider the food science experiment. Using the table and assuming the standard level of risk for Type I error, decide which is the correct critical value for this experiment.

1.699

Allen collects data from 12 male patients and 15 female patients on the types of medication that patients take on a regular basis. If Allen thinks that male patients will take more medications than females and wants to limit the likelihood of a Type I error to 5%, what would the critical value of t be for his study? (Assume that males would be the first mean in the t equation.)

1.708

Stephanie wants to compare the severity of autistic behaviors of children attending her clinic to the national average. She collects data from 25 children at her clinic and decides to conduct a single-sample t test. If Stephanie decides to use a two-tailed test and sets alpha at .05, what is the critical value of t?

2.064

Mike assesses how many hours a day 24 seniors and 15 freshmen study. If seniors study for 6.75 hours a day (s = 1.56) and freshmen study for 5.45 hours (s = 2.34), what is the value of t?

2.09

If M = 23.75, μ = 20.00, and sM = 1.50, what is the value of t?

2.50

Dr. Shoals predicts that people of different heights who walk a mile in moderately high heels and very high heels will differ in their levels of reported back pain. Thirteen people who are 5 foot, 4 inches or shorter and 14 people who are taller than 5 foot, 4 inches tall walk in 4-inch heels and 2.5-inch heels. What are the degrees for freedom for this study?

26

If n1 = 17, s1 = 11, n2 = 13, and s2 = 10, what is the standard error of the difference?

3.90

A journal article describes a study that includes these results: t(54) = 1.98, p < .05 (one-tailed). How many degrees of freedom are there in this study?

54

Shelley conducts a study on the number of traumatic symptoms experienced by combat veterans and noncombat veterans and calculates a 95% confidence interval of [4.67, 11.44]. What is the width of Shelley's confidence interval?

6.77

If a 95% CI was [3.29, 10.23], the width of the confidence interval would be:

6.94

Mikael wants to compare males and females on academic motivation. If he collects data from 69 general psychology students, how many degrees of freedom are in the study?

67

Four researchers want statistical advice on how to analyze their data. Who can conduct a single-sample t test?

Mr. White, a principal who is comparing SAT performance of students at his school to the national average

The degrees of freedom (df) for a single-sample t test is equal to:

N - 1.

The degrees of freedom for a paired-samples t test are calculated using:

N-1

Dr. David predicts that the type of bed people sleep in will influence their quality of sleep. He has people coming to his lab to sleep first in an indoor hammock and then in a conventional bed. If he uses a dependent-samples design, which of these is the proper set of hypotheses being tested?

NOT H 0: μhammock ≤ μbed H 1: μhammock > μbed ​

Fred administers a gender inventory to samples of males and females and determines the levels of androgyny in both samples. If males scored an average of 30 and females an average score of 33, what would Cohen's d be, if s2pooled = 25.00?

NOT -0.47 NOT -0.12

Given M1 = 25, s1 = 5.00, n1 = 12, M2 = 20, s2 = 6.00, and n2 = 11, what is the value of t?

NOT -0.50 NOT 3.36

Adam assessed the number of negative interactions experienced by college students in the past month. If the mean of his sample is 15.81 (sM = 0.463), what is t if he compares his sample mean to a population mean of 17.00?

NOT -2.16

Patricia is studying whether a parenting intervention reduces the stress levels of new parents compared with parents in general. If Patricia collects data from 30 new parents who completed an intervention, what would the critical value of t be if alpha is set at .05?

NOT -2.462

Given M1 = 10, s1 = 6.75, n1 = 20, M2 = 22, s2 = 8.25, and n2 = 19, what is the value of t?

NOT -3.07

In the lab experiment, if Mvideo = 5.00 on sweetness and Mlecture = 4.75 on sweetness with an sD = 1.17, calculate the t test statistic.

NOT 0.32

Lorie compares males and females on a measure of sexual jealousy. If males have a mean of 45.60 and females have a mean of 43.90, what would Cohen's d be if s2pooled = 14.75?

NOT 0.35

In the food science experiment, if Mblue = 5.60 on sweetness and Myellow = 3.42 on sweetness with an sD = 2.46, calculate the t test statistic.

NOT 0.40

If s = 15 and N = 9, what is sM?

NOT 0.60.

Erica assesses the number of visits that elementary schoolchildren make to the nurse's office. If students from School A make an average of 5.25 visits per year and students from School B make an average 3.75 visits per year, what is t if sM1-M2 = 1.23?

NOT 1.34

Gary administers a depressive symptom questionnaire to 100 people and finds that the average number of depressive symptoms in his sample is 11.75. He wants to determine whether that number is significantly more than 10, the cutoff for depression. If sM = 0.89, what is the value for t?

NOT 1.75

In the lab experiment, given that sD = 4.20, calculate the standard error of the difference for this experiment.

NOT 1.78

If a researcher conducts a two-tailed test and df = 449 and alpha is set at .01, what is the critical value of t?

NOT 1.965

In the lab experiment, using the table and assuming a conservative level of risk for Type I error, which is the correct critical value for this experiment?

NOT 2.045

In the description of the sleep study, what is the appropriate tcv for the experiment if the researcher wants to be very careful to avoid committing a Type I error?

NOT 2.110

In the description of the sleep study, what is the appropriate tcv for the experiment, if the researcher wants to use the conventional level of risk for Type I error?

NOT 2.120

What is the critical value of t if a researcher uses a one-tailed test (sample mean expected to be greater than the population) with alpha = .01 and df = 50?

NOT 2.405

Emily reports the results of her study as follows: t(47) = 3.72, p < .01 (one-tailed). Which piece of information indicates that the null hypothesis was rejected?

NOT 3.72

What is the width of the 95% confidence interval [-0.78, 5.12]?

NOT 4.86

Rich measures how far 78 patients with congestive heart failure can walk in six minutes. If the average distance is 1,073.33 feet (s = 232.85), what is sM?

NOT 5.11 NOT 2.99

Why is a repeated-measures design called a two-sample test when only one sample of cases is used in the data set?

Statisticians consider each condition in a dependent-samples study to be a sample.

Emilia randomly selects participants from her general psychology course. If she asks each participant to bring a friend who has not taken general psychology, to participate in the study as a comparison group, this would be an example of:

paired samples.

If Tina analyzes pre- and posttest data collected from the same individuals, the samples would be considered as:

paired samples.

When the same participants provide data at two different time points, the researcher is using a(n):

repeated-measures design.

Replication refers to:

repeating a study, usually with a few changes to the procedure.

Which of these is not to be considered when interpreting the results of a single-sample t test?

the sample size

When a study is underpowered, it means that:

the sample size is too small to reject the null hypothesis.

If a confidence interval is narrow but falls close to zero, what is the appropriate conclusion?

The means differ significantly and the effect size is small.

Why are single-sample t tests not commonly used in research?

The means of populations are rarely known.

When conducting an independent-samples t test, which assumption is met if cases are not influenced by other cases?

The observations are independent.

When calculating an independent-samples t test, the pooled variance is:

an estimate of the combined variance in both groups.

For which type of two-sample t test, are cases selected in such a way that one sample has no influence on the other sample?

an independent-samples t test

What statistical analysis would be appropriate for Lexus to use, if she collected data from two unrelated samples and her dependent variable was measured on a ratio scale?

an independent-samples t test

To conduct a two-sample t test, a researcher needs _____ -level dependent variable.

an interval- or ratio

An effect size:

indicates the strength of the relationship.

A first-grade teacher predicts that students taking reading quizzes early in the day will have higher scores than when they take reading quizzes late in the day. However, he is concerned that some students are more alert in the mornings than others, which would affect their scores. He is concerned that the _____ will affect their scores along with the independent variable.

individual differences

Which provides a more precise estimate of the population value?

narrower confidence intervals

When interpreting Cohen's d for an independent-samples t test, an effect size of 0.00 would indicate:

no effect size.

When would a confidence interval that is calculated for an independent-samples t test contain 0.00, indicating that a researcher has failed to reject the null hypothesis?

when the researcher has conducted a two-tailed test

In the food science experiment, which of these is the correct alternative hypothesis?

H 1: μyellow < μblue ​

D = X1 - X2 is the formula for:

difference score

D = X1 - X2 is the formula for:

difference score.

The alternative hypothesis for a single-sample t test predicts that a sample mean is:

different from a specified population mean.

The standard deviation of the sampling distribution of difference scores is called the standard:

error of the difference for difference scores.

What does sM represent, in the formula 95%CI = (M - μ) ± (tcv × sM)?

estimated standard error of the mean

What is the number compared to the critical value in the result t(26) = 5.63, p < .05?

5.63

When conducting an independent-samples t test, N is considered large when it is greater than:

50

Given M1 = 1000, M2 = 890, and sM1-M2 = 25, what is the value of t?

4.40

Assuming a two-tailed test, a researcher compares her sample to a population with a mean of 50. Which of these is a null hypothesis?

H0: mu=50

Which of these equations is correct for the 95% confidence interval for a paired-samples t test?

(M1-M2)+/-(tcv+Smd)

Which of these values would be considered a large effect size, using Cohen's d?

-1.00

If M = 20.00, μ = 22.00, and s = 1.45, what is d?

-1.38

A study reports these results: t(96) = 4.13, p < .01 (two-tailed). What is the value of the test statistic?

4.13

Stan records the blood pressures of 47 adults who regularly meditate and compares them with the blood pressure readings of adults in general. Assuming that Stan uses a single-sample t test, how many degrees of freedom does he have in his study?

46

Matt, a student in a statistics class, asks his friend to help him interpret the results of an independent-samples t test. He shows his friend the results: t(45) = 6.22 and p < .05 (two-tailed). Matt wants to know how many participants were in the study. What should Matt's friend tell him?

47

Dr. Schellenger analyzes her data using an independent-samples t test, and her results are: t(28) = 13.72, p < .05 (two-tailed). How willing was Dr. Schellenger to make a Type I error?

5%

Jim runs 100 rats through a maze and records their time in seconds. If s = 50 for the sample, what is sM?

5.00

Dr. Shoals predicts that people who walk a mile in moderately high heels will have less back pain than when they walk in very high heels. Thirteen men and 14 women walk in 4-inch heels and 2.5-inch heels. He calculates the standard deviation of the difference scores and finds sD = 3.37. The mean back pain when walking in 4-inch heels is 6.75, and when walking in 2.5-inch heels, it is 3.25. What is the t statistic for this experiment?

5.38

If Selma collects data from 10 people, how many degrees of freedom does she have in her study if she plans to conduct a single-sample t test?

9

The most commonly reported CI is the:

95% CI.

Dr. Everson is interested in examining whether participants are less stressed than usual when given stress balls (rubber balls to squeeze with their hands) before a test. He has participants take a reading comprehension test twice, first after squeezing a stress ball for 5 minutes and then later without squeezing the ball. Reading comprehension is scored on a scale of 1 to 10, with higher numbers indicating higher comprehension. The mean score with the stress ball is 9.32 and the mean score without it is 6.15—statistically different from each other. Dr. Everson should not use Cohen's d as the effect size measure in this experiment because it would:

95% confidence interval

If researchers plan to conduct a single-sample t test, how many degrees of freedom do they have if they collect data from 99 people?

98

Which of these is an advantage of using a one-tailed test rather than a two-tailed test when calculating a single-sample t test?

A one-tailed test will allow one to more easily reject the null hypothesis when the sample is extremely different from a specified value.

What information does a 95% CI provide?

A researcher can be 95 percent confident that the population value falls within the interval.

What is the difference between a single-sample z test and a single-sample t test?

A single-sample z test requires that the population standard deviation be known.

Sally compares males and females on the experience of openness. If Sally says that the effect size in her study was d = .20, what can be decided about the difference in openness between males and females?

A small difference exists between males and females.

Which best describes the relationship between sample size and tcv when conducting a single-sample t test?

As the sample size increases, tcv decreases until it becomes equivalent to zcv.

Which of these is not one of the three points attended to when interpreting a confidence interval?

Does the CI include negative numbers?

Dr. David predicts that people will have more water-related dreams when they sleep in a swaying hammock than when they sleep in a conventional bed. If he uses a dependent-samples design, which of these is the proper set of hypotheses being tested? ​

H 0: μhammock ≤ μbed H 1: μhammock > μbed ​

A student affairs director is investigating whether the method of delivery will influence the retention of knowledge about on-campus social opportunities. Twenty-nine out of an incoming class of 1,200 new students were exposed to two different means of describing the campus opportunities: a student-created online video and a live lecture given by a professor. After each exposure, participants were asked individually to fill out separate 10-item memory quizzes based on the information given in each session. These quizzes were scored for the number of items correctly remembered. The questions will address each of the steps in the hypothesis testing. In the lab experiment, when comparing the observed statistic to the critical value, what conclusion can the researchers draw?

Fail to reject the null hypothesis.

Henry conducted a one-tailed test using an independent-samples t test, with an obtained value of t = -1.978. If tcv = 1.786, what should Henry decide about the statistical significance of his analysis?

Henry should fail to reject the null hypothesis.

Kai is studying reaction time in young children. He is not sure whether to test a one-tailed or two-tailed hypothesis and asks for help. What can one tell him?

If there is a reason to believe one group will perform better, then using a one-tailed test will make it easier to reject the null hypothesis.

When interpreting the size of Cohen's d, which statement is true about negative signs?

Negative signs are ignored when determining the size of the effect.

A nationally known producer of snack cakes is preparing to launch a new lemon-flavored cake. The marketing department wants to test the differences in customer experiences with the cake, depending on the coloring that is added to the batter during baking. The department thinks that the novelty of a lemon cake with blue coloring will make the cake-eating experience and taste more enjoyable. Thirty participants, taken from among the customers who came to their on-site store, are brought to the lab and asked to taste two different cakes each: one that is tinted blue and one that is tinted bright yellow. The participants rate each cake twice on a scale from 1 to 7, with higher numbers indicating greater sweetness and greater sourness. The following questions will address each of the steps in the hypothesis testing. In the food science experiment, when drawing a conclusion about this experiment based on the 95% confidence interval, which of these is the most appropriate?

It is unlikely that the actual difference between the taste perceptions of yellow and blue cake is zero because the CI does not capture zero.

Which of these statements most accurately describes the relationship between the value of t and decisions about the null hypothesis?

Large values of t are used to reject the null hypothesis.

Refer to the description of an experiment done in a food science laboratory.A nationally known producer of snack cakes is preparing to launch a new lemon-flavored cake. The marketing department wants to test the differences in customer experiences with the cake, depending on the coloring that is added to the batter during baking. The department thinks that the novelty of a lemon cake with blue coloring will make the cake-eating experience and taste more enjoyable. Thirty participants, taken from among the customers who came to their on-site store, are brought to the lab and asked to taste two different cakes each: one that is tinted blue and one that is tinted bright yellow. The participants rate each cake twice on a scale from 1 to 7, with higher numbers indicating greater sweetness and greater sourness. The following questions will address each of the steps in the hypothesis testing.In the food science experiment, given that sD = 2.46, calculate the standard error of the difference.

NOT 5.48 NOT 1.45

What is the width of the 95% confidence interval [8.97, 11.23]?

NOT 8.52 NOT 10.67

Rosalie collected data from 83 participants. However, when she checked the table for the critical value of t, the closest value she could find without going over was 80. When reporting her results, what value should Rosalie report as her degrees of freedom?

NOT 80

If a researcher is conducting an independent-samples t test and has a sample size of 100, the study would have _____ degrees of freedom.

NOT 99

In which of these scenarios would a researcher use a single-sample t test?

NOT A social psychologist wants to test the difference between males and females and the amount of sexual harassment they have experienced.

Alex collects data on how much time psychology and biology majors spend studying each week. She expects biology majors to study more than psychology majors and calculates her tcv to be 1.660. If her t value is 2.313, what should Alex decide about the null hypothesis?

NOT Alex should fail to reject the null hypothesis. NOT Alex should reject the alternative hypothesis.

Which of these statements is true about the distributions of two populations and the effect size?

NOT As effect size increases, the amount of overlap between two populations increases.

Which statement is false about the use of a single-sample t test?

NOT Data must come from a random sample. NOT Data must be independent.

Emily and David each conduct a study on people's attitudes toward gay marriage. If Emily's 95% confidence interval is [4.23, 6.10] and David's confidence interval is [1.57, 4.09], whose study is likely to have the larger effect size, given similar standard deviations?

NOT David's study

In the lab experiment, which of these is the correct null hypothesis for this experiment?

NOT H 0: μvideo > μlecture ​

When writing the results of the music therapist's study, which of these statements would not be appropriate to include in the final part of the interpretation paragraph?

NOT In the future, replications of this study may consider using a matched-pairs experimental design to increase statistical power.

In the paragraph of the food science experiment, which of these would be most appropriate for the fourth part of the four-point interpretation paragraph?

NOT In this study, experimenters are interested in the influence that food color has on taste perception.

Refer to the description of an experiment done in a food science laboratory.A nationally known producer of snack cakes is preparing to launch a new lemon-flavored cake. The marketing department wants to test the differences in customer experiences with the cake, depending on the coloring that is added to the batter during baking. The department thinks that the novelty of a lemon cake with blue coloring will make the cake-eating experience and taste more enjoyable. Thirty participants, taken from among the customers who came to their on-site store, are brought to the lab and asked to taste two different cakes each: one that is tinted blue and one that is tinted bright yellow. The participants rate each cake twice on a scale from 1 to 7, with higher numbers indicating greater sweetness and greater sourness. The following questions will address each of the steps in the hypothesis testing.In the food science experiment, when drawing a conclusion about this experiment based on the 95% confidence interval, which of these is the most appropriate?

NOT It is possible that the actual difference between the taste perceptions of yellow and blue cake is zero because the CI does capture zero.

The symbol used to indicate the sample size for a specific experimental condition in an independent-samples t test is:

NOT N

The formula for calculating degrees of freedom for an independent-samples t test is:

NOT N - 1.

_____ hypotheses are more conservative than _____ hypotheses.

NOT One-tailed; two-tailed

A researcher has 56 pairs of participants who each experience two different experimental conditions. The value of the 95% confidence interval is [-0.7, 1.9]. The researcher should conclude that:

NOT The effect of the independent variable is quite small.

Nikki tells that the 95% CI for her study is [0.10, 4.34] and she rejected the null hypothesis. What conclusion would one reach about the effect size?

NOT The effect size is large because Nikki rejected the null hypothesis.

Shannon conducts a study and tells that when she calculated Cohen's d it was 0.00. What can be concluded about the effects of her independent variable?

NOT The independent variable and the dependent variable were perfectly correlated with one another.

If a confidence interval captures zero, what does that mean in terms of the conclusion regarding the null hypothesis?

NOT The null hypothesis is rejected and the effect size is large. NOT The null hypothesis is rejected and the effect size is small.

What happens to the t statistic as the difference between the sample mean and the population mean increases?

NOT The value of t decreases.

Cami collects data from students in upper- and lower-division courses to see whether the groups differ on levels of spirituality. If Cami collects data from 48 students and alpha is set at .01, what is tcv?

NOT ±2.014

student affairs director is investigating whether the method of delivery will influence the retention of knowledge about on-campus social opportunities. Twenty-nine out of an incoming class of 1,200 new students were exposed to two different means of describing the campus opportunities: a student-created online video and a live lecture given by a professor. After each exposure, participants were asked individually to fill out separate 10-item memory quizzes based on the information given in each session. These quizzes were scored for the number of items correctly remembered. The questions will address each of the steps in the hypothesis testing.In the lab experiment, which of these is true about the test for assumptions in this experiment?

NOT Two assumptions were violated, but they were robust to violation.

Given M1 = 50, M2 = 60, tcv = 2.020, and sM1-M2 = 5.00, what is the 95% CI?

NOT [-14.87, 0.07]

If M = 103, μ = 115, tcv = 2.228, and sM = 3.12, what is the 95% confidence interval?

NOT [-17.35, -6.65]

If M = 27, μ = 24, tcv = 1.977, and sM = .94, what is the 95% confidence interval?

NOT [0.08, 5.92]

Betsy asks two groups of students to list as many animals as they can in one minute. One group consists of biology majors, and they list an average of 13 animals; the other group consists of math majors who average 8 animals. If tcv = 1.997 and sM1-M2 = 1.75, what is the 95% CI?

NOT [0.56, 7.13]

In order to influence statistical significance, one can adjust:

NOT a Type I error. NOT the effect size. NOT a type II error

A researcher is interested to determine the levels of openness of students at his school. He collects data from 30 of his friends and classmates. The assumption that he most likely has violated is that:

NOT all data must be independent

When using a repeated-measures design, a(n) _____ is the same as a _____.

NOT independent-samples t test; dependent-samples t test NOT longitudinal design; cross-sectional design

Dr. Chapman conducted an experiment in which participants watched paint dry for 30 minutes twice, once being paid $1 and once being paid $30. When comparing the samples, he calculated t = 1.67. He assumed α = .05 with df = 5, so the tcv = ±2.571. Because the calculated value was:

NOT less than the critical value, Dr. Chapman failed to reject the null hypothesis.

Dr. Chapman conducted an experiment in which participants watched paint dry for 30 minutes twice, once being paid $1 and once being paid $30. When comparing the samples, he calculated t = 3.57. He assumed α = .01 with df = 5, so the tcv = ±4.032. Because the calculated value was:

NOT less than the critical value, Dr. Chapman failed to reject the null hypothesis. NOT less than the critical value, Dr. Chapman can reject the null hypothesis.

Determining the size of an effect in a paired-samples t test takes _____ than it does for an independent-samples t test.

NOT less thought and expertise

Dr. Aron is testing a new anxiety medication for dogs. He tested a group of 27 dogs and exposed them to the soundtrack of a thunderstorm, once with the medication and once without the medication. The time it took for the dogs to settle down was the dependent variable and ranged from 5 minutes to 35 minutes. His results showed that t(26) = 2.25, p < .05 and that 95 percent CIμDiff = [8.20, 10.37]. Given these results, it can be concluded that this study has:

NOT little practical significance. NOT little statistical significance.

Dr. Kim, a sensory psychologist studying humidity's effect on perceived temperature, used six volunteers for her study who were individually tested once in each condition. Which of the assumptions for dependent-samples t tests did she avoid violating?

NOT normality

Dr. Kim, a sensory psychologist studying humidity's effect on perceived temperature, used six volunteers for her study. Which of the assumptions for dependent-samples t tests did she violate?

NOT normality NOT independence of observations

Which assumption of an independent-samples t test is not an assumption of a single-sample t test?

NOT normality NOT independence of observations

When interpreting the results of an independent-samples t test, what information needs to be considered for a basic interpretation?

NOT pooled variance

The formula for the standard error of the difference for difference scores is _____.

NOT sd/sqrt(N-1)

In a _____ design, the participants are measured on a dependent variable before and after an intervention.

NOT single-sample

According to Cohen's standards, if the percentage of variability in the outcome variable accounted for by the explanatory variable is 25 percent, then there is _____ effect.

NOT small NOT medium NOT no

The value of the t statistic becomes _____ as the difference between the sample mean and specified value becomes _____.

NOT smaller; larger NOT larger; smaller Not smaller: smaller

Researchers calculate t for an independent-samples t test by dividing:

NOT the difference between a sample mean and a known population mean by the standard error of the mean.

If a 95% confidence interval for a paired-samples t test captures zero, then:

NOT the effect of the independent variable is quite small.

If a 95% confidence interval for a paired-samples t test is very narrow, then:

NOT the precision of the parameter value is less reliable.

When calculating the standard error of the difference for an independent-samples t test, what piece of information is not needed?

NOT the standard deviations of both groups

When one rejects the null hypothesis using a single-sample t test, the confidence interval indicates the range of scores likely containing:

NOT the true population mean of the independent variable.

If researchers decide to conduct an independent-samples t test to analyze their data, their null hypothesis would indicate that:

NOT there will be no change within a population over time. NOT the mean of their sample will not differ from a known population mean.

Dr. Everson is interested in examining whether participants are less stressed than usual when given stress balls (rubber balls to squeeze with their hands) before a test. He has participants take a reading comprehension test twice, first after squeezing a stress ball for five minutes and then later without squeezing the ball. Reading comprehension is scored on a scale of 1 to 10, with higher numbers indicating higher comprehension. The mean score with the stress ball is 7.32 and the mean score without it is 6.15—means that are not statistically different from each other. Which of these correctly describes the results?,

Not enough information is available to properly draw a conclusion.

Annie conducts a study to examine the differences in stress levels between pet owners and non-pet owners. She conducts a two-tailed test and tells that she rejected the null hypothesis. Therefore, which of these statements is true?

Pet owners' and non-pet owners' stress levels differ, but it is not known how they differ.

In the description of the sleep study, what conclusion should Dr. David make if he uses the conventional level of risk for Type I error?

Reject the null hypothesis. The type of bed influences the quality of sleep.

Which statement is true about the critical value of t when performing a one-tailed test?

The critical value of t will be positive or negative.

A researcher has an experimental group of subjects talk about an upsetting emotional event and another group talk about a neutral event. Both groups had their blood pressure monitored while giving their speeches. If the researcher expected the experimental group to show a higher blood pressure during the event, what sign would the critical value of t be, if t were calculated as Mexperimental- Mcontrol?

The critical value of t would be positive.

If a confidence interval captures zero, what does that mean in terms of the differences between two populations?

The difference between means of the populations may be equal to 0.

If the null hypothesis is rejected using a one-tailed test, which of these statements is true?

The direction of the difference between populations is known.

Use the description of an experiment done in a children's hospital.A music therapist was interested in investigating whether listening to music or composing music had an influence on both anxiety levels and oxygen saturation in children who were hospitalized for asthma-related illnesses. Thirty-two children spent 20 minutes listening to classical waltzes played on a piano. On a different day, they spent 20 minutes composing their own short pieces of music using a software program.When listening to music: For the physiological measure, the critical value for t was larger than the test statistic for the observed data. For the anxiety measure, the critical value for t was smaller than the test statistic for the observed data.When composing music: For the physiological measure, the critical value for t was larger than the test statistic for the observed data. For the anxiety measure, the critical value for t was larger than the test statistic for the observed data.When writing the results of the music therapist's study, which of these statements reflects the first point of the interpretation paragraph?

The effect of music therapy on physiological and psychological symptoms of pediatric asthma patients was examined.

What decision should a researcher make about H0 if a t value falls within the rare zone?

The researcher should reject H0.

When identifying the degrees of freedom in a study, what should a researcher do if the exact df is not listed in a table?

The researcher should use the next lowest number.

If a 95% confidence interval that is calculated for an independent-samples t test captures 0.00, what can be concluded about the null hypothesis?

There is a low probability (i.e., p < .05) that these results would be obtained if there were not actual differences between the populations.

Madison tested whether college students slept significantly less than 8 hours a night. She collected data from 100 college students and found that they slept an average of 6 hours each night. Madison calculated a 95% CI and found that her confidence interval was narrow and far from zero. What conclusion should Madison make regarding the sleep patterns of college students?

There is likely a strong effect, suggesting that college students sleep less than 8 hours each night.

Which statement is true about violation of the assumption of homogeneity of variance?

This assumption is robust if N is large (i.e., greater than 50).

If researchers use an independent-samples t test and the exact degrees of freedom in a study are not listed in a table of critical values, why should the researchers use the lower value?

Using the lower number makes it more difficult to reject the null hypothesis.

Which series of questions is in the right order?

Was the null hypothesis rejected?/How big is the effect?/How wide is the confidence interval?

A researcher has 56 pairs of participants who each experience two different experimental conditions. The mean for the first condition was is 34.27 and the mean for the second condition is 33.67. Assuming that tcv(N = 55, α = .05) = 2.004 and sMD = .65, what is the value of the 95% confidence interval?

[-0.7, 1.9]

If M = 5, μ = 2, tcv = 2.017, and sM = 1.88, what is the 95% confidence interval?

[-0.79, 6.79]

Given M1 = 110, M2 = 103, tcv = 1.964, and sM1-M2 = 10.00, what is the 95% CI?

[-12.64, 26.64]

If M = 78, μ = 75, tcv = 2.086, and sM = 2.63, what is the 95% confidence interval?

[-2.49, 8.49]

Rebecca assesses the number of text messages that students at her school send in a given day. On average, students in her sample sent 55 messages a day (sM = 6.81). If μ = 50 and tcv = 2.021, what is the 95% CI?

[-8.76, 18.76]

Shawndai measures happiness in a sample of individuals who meditate on a regular basis and a group of individuals who do not meditate. The means of both groups are 37 and 30, respectively. If tcv = 2.101 and sM1-M2 = 3.25, what is the 95% CI?

[0.17, 13.83]

Refer to the description of an experiment done in a food science laboratory.A nationally known producer of snack cakes is preparing to launch a new lemon-flavored cake. The marketing department wants to test the differences in customer experiences with the cake, depending on the coloring that is added to the batter during baking. The department thinks that the novelty of a lemon cake with blue coloring will make the cake-eating experience and taste more enjoyable. Thirty participants, taken from among the customers who came to their on-site store, are brought to the lab and asked to taste two different cakes each: one that is tinted blue and one that is tinted bright yellow. The participants rate each cake twice on a scale from 1 to 7, with higher numbers indicating greater sweetness and greater sourness. The following questions will address each of the steps in the hypothesis testing.Consider the food science experiment. The proper APA style for this result is:

[1.26, 3.10]

In the lab experiment, what if the results had been different? If Mvideo = 6.00 on sweetness and Mlecture = 8.75 on sweetness with an sD = 0.85, which of these is the correct 95%confidence interval for this result?

[2.31, 3.19]

Marcus conducts a study on whether patients at his clinic experience higher amounts of psychological distress than do patients in general. If there is no difference in the distress levels and Marcus concludes that his sample differs from the population, he has committed:

a Type I error.

Kamal is in the process of collecting data for which he will need to use a single-sample t test, but he is unsure what sample size to use. You should advise Kamal to use:

a large sample, because larger samples are associated with greater degrees of freedom.

A personality researcher proposes that a person's introversion will decrease with age. She identifies introverted 5-year-olds and then tests them again every six years until they are 70. What kind of research design has the researcher used?

a longitudinal design

Mary measures the number of hours per week that males and females spend at the gym. If males averaged 4 hours per week and females averaged 5 hours per week, how large will the effect size be if s2pooled = 3.50?

a medium effect

An effect size of d = 0.65 is classified as :

a medium effect.

A student affairs director is investigating whether the method of delivery will influence the retention of knowledge about on-campus social opportunities. Twenty-nine out of an incoming class of 1,200 new students were exposed to two different means of describing the campus opportunities: a student-created online video and a live lecture given by a professor. After each exposure, participants were asked individually to fill out separate 10-item memory quizzes based on the information given in each session. These quizzes were scored for the number of items correctly remembered. The questions will address each of the steps in the hypothesis testing.In the lab experiment, which of these statistical tests is most appropriate for this experiment?

a paired-sample t test

In the food science experiment, which statistical test is most appropriate for this experiment?

a paired-samples t test

In a _____ design, the same participants are measured on a dependent variable under two different conditions or different situations

a repeated-measures design

It is appropriate to use a single-sample t test when:

a sample mean is being compared to a population mean with an unknown standard deviation

Given M1 = 100, M2 = 103, and s2pooled = 200.00, how large is the effect size?

a small effect

Jillian conducted a study on two groups of rats placed in a maze. She exposed one group of rats to loud noise and the other group of rats to silence. She wants to compare how long it took both groups of rats to successfully navigate the maze. What statistic should Jillian use to analyze her data?

a two-sample t test

After a researcher states an alternative hypothesis, the null hypothesis would be stated in a way that makes the two hypotheses _____ and _____.

all-inclusive; mutually exclusive

Cohen's d is an improper choice for reporting the effect size in paired-samples t tests because it would:

also include the effect of individual differences among the participants.

If the null hypothesis is true and no difference exists between the mean of a sample and a specified value, the value of the t statistic will:

be 0.00.

Dr. Sternberg is interested in examining whether participants are more creative than usual in colorful surroundings. She has participants write short stories first in a room decorated with rainbows and then in a room that is painted dark gray. Raters later score the stories on creativity on a scale of 1 to 10, with higher numbers indicating higher creativity. The mean score for the rainbow room was 8.57, and the mean score for the gray room was 6.65—statistically different from each other. Dr. Sternberg can conclude that:

being in a rainbow room yields higher creativity than being in a gray room.

Which of these t tests would be considered two-sample t tests?

both independent and paired-samples t tests

Dr. David predicts that the type of bed people sleep in will influence their quality of sleep. He has 18 people come to his lab to sleep first in an indoor hammock and then in a conventional bed. He uses a dependent-samples design and calculates a test statistic of t = 2.23. Using the excerpt from the t table below, answer these questions.​In the description of the sleep study, if the researcher switches from a one-tailed to a two-tailed hypothesis, the _____ of t goes up as _____.

critical value; the degrees of freedom go down

Kenzie is conducting a study and plans to use a single-sample t test. If she increases her sample size from 30 to 100 participants, the critical value of t will:

decrease.

A study where the calculated confidence interval _____ is most indicative of a large effect size.

falls far away from 0.00

Maria tells that the standard deviations in her independent samples are equal to each other. Based on this information, which of the assumptions is not violated by her data?

homogeneity of variance

The calculation of a confidence interval for an independent-samples t test tells a researcher:

how close together the two population means may be.

A confidence interval does not give information about:

how far away the CI is from one.

If two samples do not have the same number of individuals in each, the samples must be:

independent samples.

It is most appropriate to use a matched-pairs design in a study that examines:

interpersonal rapport with strangers after engaging in either a cooperative or a competitive task.

Chad asks his friend to help him interpret a box-and-whisker plot in a journal article he recently read. He is not sure what the box represents. His friend should tell him that the box represents the:

interquartile range.

When using an independent-samples t test, it is better to have a confidence interval that:

is narrow.

What is the chance that a Type I error was made in the result t(26) = 5.63, p < .05?

less than 5percent

Dr. Chapman conducted an experiment in which participants watched paint dry for 30 minutes twice, once being paid $1 and once being paid $30. When comparing the samples, he calculated t = 5.57. He assumed α = .05 with df = 5, so the tcv = ±2.571. Because the calculated value was:

less than the critical value, Dr. Chapman rejected the null hypothesis.

Dr. Aron is testing a new anxiety medication for dogs. He tested a group of 27 dogs and exposed them to the soundtrack of a thunderstorm, once with the medication and once without the medication. The time it took for the dogs to settle down was the dependent variable and ranged from 5 minutes to 35 minutes. His results showed that t(26) = 2.25, p < .05 and that 95 percent CIμDiff = [20.25, 27.37]. Given these results, it can be concluded that this study has:

little practical significance.

When a researcher follows the same group of participants over time, the researcher is using a(n):

longitudinal design.

When the researcher groups participants into sets of two based on how similar they are on potentially confounding variables, the researcher is using a:

matched-pairs design.

In a box-and-whisker plot, the line in the center of the box indicates the:

median of the sample.

Dr. Kim, a sensory psychologist studying humidity's effect on perceived temperature, used six volunteers for her study; each volunteer was individually tested once in each condition. She examines the _____ in order to avoid violating the normality assumption for dependent-samples t tests.

normality of the population of difference scores

The null hypothesis for a single-sample t test examining a two-tailed test predicts that a sample mean is:

not different from a specified population mean.

Just as with an independent-samples t test, the critical value for a dependent-samples test depends on all of the following information, except for the:

number of times the participants were measured.

The homogeneity of variance assumption likely to be violated when the standard deviation:

of one sample is more than twice the standard deviation of the other sample.

Liz believes that maximizers (people who feel pressured to make the best possible decision) experience higher levels of depressive symptoms than do people in general. This is an example of a(n) _____ hypothesis.

one-tailed

When the independent variable has a meaningful influence on the dependent variable, then there is:

practical significance.

When a result is not statistically significant, it cannot be:

practically significant

When conducting an independent-samples t test, the assumption of random samples means that both samples are:

randomly selected from the population.

The whiskers extending from the box of a box-and-whisker plot indicate the:

range of scores in a sample.

The percentage of variability in the outcome variable accounted for by the explanatory variable:

ranges from 0 percent to 100 percent.

When considering the assumptions for a paired-samples t test, the normality assumption:

refers to the normality of difference scores only.

The standard error of the difference is the:

standard deviation for the sampling distribution of the difference between sample means.

When calculating the test statistic value for an independent-samples t test, the differences between the mean are divided by the:

standard error of the difference.

To calculate the width of a confidence interval, a researcher would:

subtract the lower limit from the upper limit.

Which of these demonstrates the proper APA format for the results of a paired-samples t test?

t(26) = 5.63, p < .05

Which of these is reported accurately in APA style for a study with 37 people and a statistically significant result with an obtained t value of 3.22?

t(36) = 3.22, p < .05

What would tcv be if one is conducting a two-tailed test and alpha is set at .05?

tcv cannot be determined without knowing the sample size.

Bryce wants to know whether the intelligence of children in his school is higher than the national average. To test this, Bryce administers a childhood intelligence test to 50 children at the local elementary school. During data collection, Bryce accidentally tests one of the students twice. Which of these assumptions of a single-sample t test did Bryce violate?

the assumption that all data must be independent

Destiny wants to know whether gender predicts depressive symptoms in patients with heart disease. She assesses the number of depressive symptoms experienced by a large sample of patients and finds that the data on depressive symptoms are positively skewed. Which assumption of a single-sample t test has Destiny most likely violated?

the assumption that the dependent variable is normally distributed

What does "cv" stand for in the equation for the 95% confidence interval for a paired-samples t test? The equation is 95% CIμDiff = (M1 - M2) ± (tcv × sM D)?

the critical value of t, two-tailed, α = .05, df = N - 1

If a nonrobust assumption is violated in a repeated-measures design, then:

the researcher should not proceed with the paired-samples t test.

If a 95% confidence interval for a paired-samples t test comes close to zero, then:

the effect of the independent variable is quite small.

Which of these factors does not influence the size of the critical value of t?

the effect size

What information is used to determine the sign of the critical value of t when performing a one-tailed test?

the order of subtraction and what the sign should be

When calculating Cohen's d for an independent-samples t test, what value is used as the denominator?

the pooled variance

When evaluating the width of a confidence interval (i.e., wide versus narrow), which of these should be considered?

the possible range of scores on the raw variable

If a robust assumption is violated in a repeated-measures design, then:

the researcher can proceed with the statistical test just as with a nonrepeated-measures design.

What does "sMD" stand for in the equation for the 95% confidence interval for a paired-samples t test? The equation is 95% CIμDiff = (M1 - M2) ± (tcv × sM D)?

the standard error of the difference for the difference scores

Which piece of information is not needed to calculate Cohen's d?

the standard error of the mean

What does the "t" stand for in the result t(26) = 5.63, p < .05?

ttest

If a researcher expects his sample to differ from a population but is not sure if the population will exhibit more or less of a characteristic, the researcher should make a(n):

two-tailed hypothesis.

Lonieka is interested in studying gender differences in sexual and emotional jealousy. She expects males and females to differ on both measures, but she is not sure how males and females will differ. One should advise her to choose a(n):

two-tailed test.

A social worker hypothesizes that sustained and positive physically active play will lead to young adults who are less likely to use physical aggression. For the researcher to be more confident that any observed difference among the groups is due to the presence of this kind of play, she should:

use a matched-pairs design to create pairs of participants with similar levels of aggression.

One reason why the paired-samples t tests are so common is that many experimental situations:

use a pre-post design with the dependent variable measured before and after the independent variable is applied.

A first-grade teacher predicts that students who take reading quizzes on yellow paper will have higher scores than when they take reading quizzes on white paper. If she uses only her current class to test this hypothesis, she is using a:

within-subjects design.

What is the critical value of t for an independentsamples t test if a researcher conducts a two-tailed test, alpha is set at .05, and there are 40 degrees of freedom?

±2.021