Deck 10: Testing Means: Related-Samples T Test With Confidence Intervals

Question 1

Which of the following is a type of related samples design in which different participants are actually observed in each group,but treated statistically as if they are the same persons in each group.

A)repeated measures design
B)matched samples design
C)pre-post design
D)within-subjects design

Answer 1

matched samples design

Question 2

For the related samples t test,assuming that all other values remain constant,then as samples size increases,

A)the value of the test statistic increases
B)the power to detect an effect increases
C)the estimate for standard error decreases
D)all of the above

Answer 2

all of the above

Question 3

Each of the following is an advantage for using the related samples design,except

A)it can be more practical
B)it minimizes standard error
C)it increases the power of a research design
D)it increases the variability measured in a study

Answer 3

it increases the variability measured in a study

Question 4

One difference between a repeated measures design and a matched samples design is that

A)only one design is a type of related sample design
B)only one design increases the power to observe an effect
C)only one design involves observing the same participants in each group
D)only one design eliminates between-persons variability

Question 5

All other things being equal,as the sample size increases,what happens to the critical value for a related samples t test (or for any t test,for that matter)?

A)The critical value increases.
B)The critical value decreases.
C)The critical value does not change.
D)It depends on the value of the test statistic.

Question 6

A researcher records the time it takes (in seconds)for participants to respond (by pressing a key)to a familiar versus an unfamiliar word flashed onto a computer screen.In this study,the difference in response time for each participant is compared.The type of design described here is called a

A)repeated measures design
B)matched samples design
C)both A and B

Question 7

The denominator of the test statistic for a related samples t test

A)compares mean differences observed to the mean differences stated in a null hypothesis
B)is the sum of the difference scores for each participant
C)provides an estimate of the error associated with the original scores
D)provides an estimate of the error associated with the difference scores

Question 8

All other things being equal,as the degrees of freedom increase,what happens to the critical value for a related samples t test (or for any t test,for that matter)?

A)The critical value increases.
B)The critical value decreases.
C)The critical value does not change.
D)It depends on the value of the test statistic.

Question 9

A researcher matched 30 participants on intelligence (hence 15 pairs of participants),and then compared differences in emotional responsiveness to two experimental stimuli between each pair.For this test,what are the critical values,assuming a two-tailed test at a .05 level of significance?

A)±2.042
B)±2.045
C)±2.131
D)±2.145

Question 10

What are the degrees of freedom for the related samples t test?

A)(n_D - 1)
B)(n - 1)(n - 1)
C)(n - 1)+ (n - 1)
D)(n - 1)- (n - 1)

Question 11

The test statistic for a related samples t test makes tests concerning a single sample of

A)raw scores
B)difference scores
C)participant scores
D)original data

Question 12

Each of the following is an estimate of error for a t test,except

A)standard error
B)estimated standard error
C)estimated standard error for the difference
D)estimated standard error for difference scores

Question 13

A researcher records the strength of a conditioned response among 12 rats in the presence and absence of conditioned cues.If he computes a related samples t test at a .05 level of significance (two-tailed test),then what are the critical values for this test?

A)±2.201
B)±2.179
C)±1.796
D)±1.782

Question 14

Which of the following is the numerator of the test statistic for the related samples t test?

A)the sum of the difference scores for each participant
B)the value of the test statistic plus the degrees of freedom
C)the mean difference observed minus the mean difference stated in a null hypothesis
D)estimated standard error for difference scores

Question 15

A researcher asks a sample of brothers and sisters to rate how positive their family environment was during childhood.In this study,the differences in ratings between each brother and sister pair were compared.The type of design described here is called a

A)repeated measures design
B)matched samples design
C)both A and B

Question 16

A type of related samples design in which participants are observed more than once is called a

A)repeated measures design
B)matched pairs design
C)matched samples design
D)both B and C

Question 17

How does the test statistic differ for a t test using the repeated measures versus the matched samples design?

A)Using the matched samples design,we analyze raw scores,whereas using the repeated measures,we analyze difference scores before computing the test statistic for the related samples t test.
B)Using the repeated measures design,we analyze raw scores,whereas using the matched samples design,we analyze difference scores before computing the test statistic for the related samples t test.
C)Using the repeated measures design,we treat each pair of scores as related;we do not treat each pair of scores as related using the matched samples design.
D)The test statistic for the repeated measures and the matched samples designs do not differ;the test statistic is computed the same.

Question 18

A researcher compares the difference in the amount of texting by students in class during the first week and last week of classes.The type of design described here is called a

A)repeated measures design
B)matched samples design
C)both A and B

Question 19

A researcher records the level of attention among 18 students during an interactive and lecture portion of a single class.If she computes a related samples t test at a .05 level of significance (two-tailed test),then what is the critical value for this test?

A)±1.734
B)±1.740
C)±2.110
D)±2.101

Question 20

Which of the following is the denominator of the test statistic for the related samples t test?

A)standard error
B)estimated standard error
C)estimated standard error for the difference
D)estimated standard error for difference scores

Question 21

To compute a related samples t test,a researcher has to know many values.Which of the following is NOT a value that the researcher must know to compute this test?

A)the estimated standard error for difference scores
B)the population variance of difference scores
C)the sample size or number of pairs of scores
D)the sample variance of difference scores

Question 22

A researcher placed male rodents in the presence and absence of a conspecific male.Cortisol (a stress hormone)levels were compared at both times.What type of t test is most appropriate for this study?

A)one-sample t test
B)two-independent sample t test
C)related samples t test
D)There is not enough information to answer this question.

Question 23

A researcher conducts a study in which the same participants are observed across each level of the independent variable.If there are only two levels of the independent variable,then what type of t test is appropriate for this study?

A)one-sample t test
B)two-independent sample t test
C)related samples t test
D)There is not enough information to answer this question.

Question 24

Each of the following is needed to compute the estimated Cohen's d,except

A)the mean difference
B)the standard error
C)the standard deviation of difference scores

Question 25

A researcher conducts a study in which the population variance of difference scores between two groups is unknown.What type of t test is most appropriate for this study?

A)one-sample t test
B)two-independent sample t test
C)related samples t test
D)There is not enough information to answer this question.

Question 26

To increase the value of estimated Cohen's d,a researcher increases the sample size.Will this change the value of d?

A)Yes;as sample size increases,effect size increases.
B)No;as sample size increases,effect size decreases.
C)No;the sample size is not used to compute effect size.
D)Yes;as sample size increases,effect size decreases.

Question 27

A researcher sampled 25 participants and measured their alcohol consumption (in ounces)in both a home and a bar setting.If the mean difference in satisfaction ratings for this sample was 11.4±2.5 ( ),then what is the decision at a .05 level of significance?

A)Alcohol consumption significantly differed,t(23)= 4.56.
B)Alcohol consumption significantly differed,t(24)= 4.56.
C)Alcohol consumption significantly differed,t(23)= 22.80.
D)Alcohol consumption significantly differed,t(24)= 22.80.

Question 28

A researcher computes the mean difference in locomotion in a sample of 12 rats before and 30 minutes after an injection of amphetamine.Rats were placed in a box with infrared beams.The number of times rats crossed the beams was used as a measure of locomotion.The mean difference in locomotion was 6.2±8.4 ( ),and this difference was significant.What is the effect size for this result using estimated Cohen's d?

A)d = 0.74 (medium effect)
B)d = 1.36 (medium effect)
C)d = 0.74 (large effect)
D)d = 1.36 (large effect)

Question 29

A professor computes the mean difference in exam scores before and after a lecture as 9.0±14.5 ( ),and this difference was significant.What is the effect size for this result using estimated Cohen's d?

A)d = 0.62 (medium effect)
B)d = 1.61 (medium effect)
C)d = 0.62 (large effect)
D)d = 1.61 (large effect)

Question 30

All other things being equal,reducing the level of significance from .05 to .01 will ________ the value of the test statistic for a related samples t test.

A)increase
B)decrease
C)have no effect on

Question 31

A researcher tests how well participants know their spouse while under hypnosis,and again without hypnosis.It was hypothesized that participant responses would be more accurate (greater number of correct responses)when under hypnosis.The mean number of correct responses was M = 5.30 under hypnosis and M = 3.40 without hypnosis in a sample of 30 participants.If the estimated standard error for difference scores was 2.52,then what is the decision at a .05 level of significance (two-tailed test)?

A)Retain the null hypothesis;responses were more accurate under hypnosis.
B)Retain the null hypothesis;responses were not more accurate under hypnosis.
C)Reject the null hypothesis;responses were more accurate under hypnosis.
D)Reject the null hypothesis;responses were not more accurate under hypnosis.

Question 32

Which of the following is an assumption for computing the related samples t test?

A)The population being sampled from is normally distributed.
B)The population variance of difference scores is unknown.
C)Samples are related or matched between groups,but not within groups.
D)all of the above

Question 33

A researcher conducts a study in which different participants are independently observed within groups,and the same participants are observed between groups.If there are only two groups,then what type of t test is appropriate for this study?

A)one-sample t test
B)two-independent sample t test
C)related samples t test
D)There is not enough information to answer this question.

Question 34

A researcher selects a sample of 24 college students and has them rate their liking for two advertisements aimed at improving the image of the college.The researcher finds that liking ratings significantly differed,t = 2.900.Use omega-squared to compute the proportion of variance for this result.

A) = 0.29
B) = 0.24
C) = 0.21
D)There is not enough information to answer this question.

Question 35

A researcher selects a sample of 36 dog owners and measures their responsiveness to pictures depicting the humane and inhumane treatment of dogs.The researcher finds that responsiveness significantly differed,t = 3.243.Use eta-squared to compute the proportion of variance for this result.

A) = 0.21
B) = 0.23
C) = 0.25
D)There is not enough information to answer this question.

Question 36

A professor compares scores on a competency exam among students at two times during a single semester.What type of t test is most appropriate for this study?

A)one-sample t test
B)two-independent sample t test
C)related samples t test
D)There is not enough information to answer this question.

Question 37

A researcher sampled 16 couples and measured the mean difference in their marital satisfaction.Each couple was paired and the differences in their ratings (on a 7-point scale)were taken.If the mean difference in satisfaction ratings for this sample was 1.8±2.0 ( ),then what is the decision at a .05 level of significance?

A)Satisfaction ratings do not significantly differ,t(14)= 0.90.
B)Satisfaction ratings do not significantly differ,t(15)= 0.90.
C)Satisfaction ratings significantly differ,t(14)= 3.60.
D)Satisfaction ratings significantly differ,t(15)= 3.60.

Question 38

A researcher selected a sample of 24 participants and observed their behavior at two times.The result of a related samples t test at a .05 level of significance was t = 2.68.Which of the following correctly describes the result of this test?

A)A related samples t test is the correct tests for this study;the result of the test is not significant
B)A related samples t test is the correct tests for this study;the result of the test is significant
C)The result of the test cannot be appropriately interpreted because the related samples t test was not the correct test for this study;the researcher should have computed a two-independent sample t test
D)The result of the test cannot be appropriately interpreted because the related samples t test was not the correct test for this study;the researcher should have computed a one-sample t test

Question 39

A researcher conditions rats to fear a tone that was sounded just prior to a brief shock.To measure fear following this conditioning,she records the number of lever presses by each rat in the presence and in the absence of the tone.It was hypothesized that reduced lever pressing in the presence of the tone was evidence for a conditioned fear response in rats.If the researcher tested this hypothesis at a .05 level of significance (two-tailed test),then what is her decision if she computes t = ñ2.842 in a sample of 8 rats.

A)Retain the null hypothesis;there is evidence for a conditioned fear response.
B)Retain the null hypothesis;there is not evidence for a conditioned fear response.
C)Reject the null hypothesis;there is evidence for a conditioned fear response.
D)Reject the null hypothesis;there is not evidence for a conditioned fear response.

Question 40

All other things being equal,increasing the sample size will ________ the value of the test statistic for a related samples t test.

A)increase
B)decrease
C)have no effect on

Question 41

When reporting data in a results section,it is ____ necessary to identify the type of t test computed.

A)always
B)not
C)usually
D)significantly

Question 42

The estimated standard error for difference scores is in the denominator of the test statistic for the related samples t test.

Question 43

Using APA format,which value is typically given in parentheses when reporting the results for a t test?

A)The degrees of freedom.
B)The estimate for standard error.
C)The value of the test statistic.
D)The level of significance.

Question 44

Participants can be matched through experimental manipulation or through natural occurrences to use the matched-pairs design.

Question 45

The related samples design can ________ the power to detect an effect by making the standard error ________.

A)increase;smaller
B)increase;larger
C)decrease;smaller
D)decrease;minimal

Question 46

To compute the related samples t test,we assume independence within groups,but not between groups.

Question 47

An example of matching by experimental manipulation would be if we matched participants based on their gender (male,female).

Question 48

The related samples t test makes tests concerning the difference between pairs of measured scores.

Question 49

The repeated measures design,but not the matched-pairs design,is associated with greater power to detect an effect compared with the independent samples design.

Question 50

Compared to the two-independent sample t test,the related samples design decreases

A)power
B)effect size
C)standard error
D)significance

Question 51

Two researchers analyze the same data set.Researcher A uses a two-independent sample t test and decides to retain the null hypothesis.Researcher B uses a related samples t test and decides to reject the null hypothesis.Which of the following is a likely explanation for the disparity in the decisions made.

A)The two-independent sample t test had greater power to detect the effect.
B)The two-independent sample t test was associated with fewer degrees of freedom.
C)The related samples t test had greater power to detect the effect.
D)The related samples t test was associated with more degrees of freedom.

Question 52

Which of the following identifies a large effect size for a t test?

A) = .25
B)d = .76
C) = .20
D)t = 2.32.

Question 53

The test statistic for the related samples t test is equivalent to the test statistic for the two-independent sample t test.

Question 54

The degrees of freedom for the related samples t test is the number of pairs of participants minus one,and not always the total number of participants minus one.

Question 55

The related samples design can ________.

A)eliminate within groups error
B)reduce power
C)increase standard error
D)be more practical

Question 56

"Elementary school children spent significantly more time reading the presence of a teacher than when the teacher was absent,t(7)= 2.804,p < .05 ( $\omega$ ²=0.46)." In this related samples t test,how many participants were observed?

A)5
B)6
C)7
D)8

Question 57

Which of the following is an advantage for selecting related samples compared to selecting independent samples in behavioral research?

A)Selecting related samples can be more practical.
B)Selecting related samples minimizes standard error.
C)Selecting related samples increases power.
D)All of the above.

Question 58

The related samples t test is associated with no degrees of freedom.

Question 59

The degrees of freedom for the related samples t test is the number of difference scores minus one.

Question 60

A study in which 26 participants are observed two times is associated with 26 degrees of freedom for a related samples t test.

Question 61

The estimated standard error for difference scores is the denominator of the test statistic for a related samples t test.

Question 62

Selecting related samples can be more practical in that selecting related samples may provide a better way to test your hypotheses.

Question 63

The estimate for standard error is placed in the numerator of the test statistic for a related samples t test.

Question 64

If a related samples t test is significant,then it will also be associated with a large effect size.

Question 65

Using the same data,a related samples t test is more likely than a two-independent sample t test to result in a decision to reject the null hypothesis.

Question 66

Both estimates of proportion of variance, and ,are computed the same for independent and related samples t tests.

Question 67

A researcher computes a related samples t test with t(20)= 2.096.In this example,the decision is to reject the null hypothesis for a one-tailed test,but not for a two-tailed test.

Question 68

The decision is to reject the null hypothesis for the following related samples t test: t(23)= 3.02,p < .05 (d = .18).

Question 69

Original pairs of scores are first reduced to difference scores before computing the test statistic for the related samples t test.

Question 70

The type of t test that was used is typically reported in a data analysis section that precedes the results section in an APA-style paper.

Question 71

Selecting related samples minimizes standard error and increases power.

Question 72

The estimated Cohen's d for the related samples t test uses the sample standard deviation for difference scores as an estimate of the standard deviation of difference scores in the population.

Question 73

The assumptions for a related samples t test are the same as those for the two-independent sample t test.

Question 74

A researcher computes d = .26.Hence,it is appropriate to conclude that 26% of the variability in the dependent variable can be accounted for by the presence of the independent variable.

Question 75

To summarize a related samples t test,we report the test statistic,critical values,and p value.

Question 76

A researcher computes d = .12,which is a small effect size.

Question 77

As the value of the test statistic for a related samples t test increases,the likelihood of deciding to retain the null hypothesis also increases.

Question 78

Selecting related samples increases standard error and reduces power.

Question 79

The assumptions for a related samples t test apply to both the repeated measures and matched-pairs designs.