Deck 10: Inferential Statistics: Two-Group Designs

Question 1

When using an independent-groups t-test,the difference between the means is divided by the standard error of the

A)mean.
B)standard deviation.
C)difference between means.
D)difference between standard deviations.

Answer 1

C

Question 2

In a research study comparing two conditions,researchers obtain 24 scores from each condition.If this was a within-subjects design,then there were _____ participants in the study.

A)24
B)25
C)26
D)48

Answer 2

A

Question 3

If,after calculating an independent-groups t-test you find that it is equal to zero,then

A)the two sample means differ significantly.
B)the two sample means do not differ significantly.
C)you have done something wrong.
D)the two population means differ significantly.

Answer 3

B

Question 4

The null hypothesis for a two-tailed independent-groups t-test states that

A)H₀: $\mu$ ₁ $\neq$ $\mu$ ₂.
B)H₀: $\mu$ ₁ = $\mu$ ₂.
C)H_a: $\mu$ ₁ $\neq$ $\mu$ ₂.
D)H_a: $\mu$ ₁ = $\mu$ ₂.

Question 5

Which of the following are aspects of a study that can increase power?

A)greater differences produced by the independent variable
B)smaller variability of raw scores in each condition
C)increased sample size
D)all of the options are correct

Question 6

Imagine that you conducted an independent-groups t-test with 12 participants in each group.For a two-tailed test,the t_cv at $\alpha$ = .05 would be

A) $\pm$ 1.717.
B) $\pm$ 2.074.
C) $\pm$ 1.711.
D) $\pm$ 2.064.

Question 7

For a correlated-groups t-test,the null hypothesis states that

A)H₀: $\mu$ ₁- $\mu$ ₂ = 0.
B)H₀: $\mu$ ₁- $\mu$ ₂ > 0.
C)H_a: $\mu$ ₁- $\mu$ ₂ = 0.
D)H_a: $\mu$ ₁- $\mu$ ₂ > 0.

Question 8

An independent-groups t-test

A)compares sample means for two related groups.
B)compares sample means for two unrelated groups.
C)compares standard deviations for two unrelated group.
D)compares sample means for three or more unrelated groups.

Question 9

For a correlated-groups t-test,the alternative hypothesis states that

A)H₀: $\mu$ ₁- $\mu$ ₂ = 0.
B)H₀: $\mu$ ₁- $\mu$ ₂ > 0.
C)H_a: $\mu$ ₁- $\mu$ ₂ = 0.
D)H_a: $\mu$ ₁- $\mu$ ₂ > 0.

Question 10

If a researcher reported for an independent-groups t-test that t(18)= 2.90,p< .01,how many participants were there in the study?

A)18
B)20
C)10
D)9

Question 11

If researchers reported that,for a correlated-groups design,t(20)= 3.57,p<.05,you can conclude that

A)the null hypothesis should be rejected.
B)that you should fail to reject the null hypothesis.
C)the alternative hypothesis was incorrect.
D)the study needs to be repeated.

Question 12

As sample variance _____,the value of the t-test _____.

A)increases; increases
B)decreases; decreases
C)increases; decreases
D)increases; stays the same

Question 13

Which of the following is not an assumption of the t-test for independent groups?

A)The data are interval or ratio.
B)The underlying distributions are bell-shaped.
C)The observations are independent.
D)There is not homogeneity of variance.

Question 14

If an independent-groups t-test has 7 participants in each group,then the degrees of freedom are

A)7.
B)14.
C)6.
D)12.

Question 15

The alternative hypothesis for a two-tailed independent-groups t-test states that

A)H₀: $\mu$ ₁ $\neq$ $\mu$ ₂.
B)H₀: $\mu$ ₁ = $\mu$ ₂.
C)H_a: $\mu$ ₁ $\neq$ $\mu$ ₂.
D)H_a: $\mu$ ₁ = $\mu$ ₂.

Question 16

For an independent-groups t-test,the value of Cohen's d describes

A)the size of the treatment effect.
B)the chance of a Type I error.
C)the chance of a Type II error.
D)the overall chance level in the experiment.

Question 17

If the null hypothesis is true,then the t-test should be close to

A)0.00.
B) $\pm$ 1.65.
C) $\pm$ 1.96.
D) $\pm$ 3.00.

Question 18

If researchers reported that,for a correlated-groups design,t(20)= 3.57,p<.05,you can conclude that

A)a total of 21 people participated in the study.
B)a total of 22 people participated in the study.
C)a total of 40 people participated in the study.
D)the number of participants cannot be determined.

Question 19

Which of the following t-test results has the greatest chance of statistical significance?

A)t(28)= 1.70
B)t(14)= 1.70
C)t(18)= 1.70
D)t(10)= 1.70

Question 20

If a correlated-groups t-test and an independent-groups t-test both have df=16,which experiment used more participants?

A)they both used the same number of participants (n=18)
B)they both used the same number of participants (n=17)
C)the correlated-groups t-test
D)the independent-groups t-test

Question 21

Which of the following is not an assumption of the Wilcoxon matched-pairs signed-ranks T test?

A)The data are ratio,interval or ordinal in scale,all of which must be converted to ranked (ordinal)data before conducting the test.
B)The underlying distribution is not normal.
C)The observations are independent.
D)The other alternatives are all assumptions of the Wilcoxon matched-pairs signed-ranks test.

Question 22

What are the assumptions of the Wilcoxon rank-sum test?

Question 23

When using a correlated-groups t-test,df =

A)n₁ + n₂ - 2.
B)n - 1.
C)n₁ + n₂ - 1.
D)n - 2.

Question 24

In a correlated-groups design,if n = 20,then df =

A)20.
B)19.
C)21.
D)40.

Question 25

Which of the following is true regarding the $\chi$ ² test of independence?

A)It requires a numerical (quantitative)score for each individual.
B)The sample must be random.
C)Population parameters such as $\mu$ and $\sigma$ must be known.
D)The observations must not be independent.

Question 26

Wilcoxon rank-sum test is to _____ as Wilcoxon matched-pairs signed-ranks T test is to _____.

A)ordinal data; nominal data
B)interval data,ordinal data
C)between-subject design; within-subjects design
D)within-subjects design; between-subjects design

Question 27

Chi-square tests are to _____ data as Wilcoxon tests are to _____ data.

A)ordinal; interval
B)nominal; ordinal
C)ordinal; nominal
D)ratio,ordinal

Question 28

Imagine that you conducted a correlated-groups t-test with 12 participants.For a two-tailed test,the t_cv at $\alpha$ = .05 would be

A) $\pm$ 1.796.
B) $\pm$ 2.201.
C) $\pm$ 1.782.
D) $\pm$ 2.179.

Question 29

The Wilcoxon tests are used with _____ data.

A)ordinal
B)interval
C)ratio
D)nominal

Question 30

When using the Wilcoxon tests,the obtained value must be ______ the critical value in order to establish statistical significance.

A)less than or equal to
B)greater than or equal to
C)greater than
D)equal to

Question 31

The _____ is a nonparametric inferential test for comparing sample medians of two independent groups of scores.

A)Wilcoxon matched-pairs signed-ranks T test
B)Wilcoxon rank-sum test
C) $\chi$ ² test for independence
D) $\chi$ ² goodness-of-fit test

Question 32

Which of the following is not an assumption of the $\chi$ ²-test?

A)It is a nonparametric test.
B)It is appropriate only for ordinal data.
C)The frequency in each cell should be at least 5.
D)The sample should be randomly selected.

Question 33

One advantage of the correlated-groups t-test over the independent-groups t-test is that it reduces the error variance due to

A)the degrees of freedom.
B)the independent variable.
C)the dependent variable.
D)individual differences.

Question 34

The _____ is a nonparametric inferential test for comparing sample medians of two dependent or related groups of scores.

A)Wilcoxon matched-pairs signed-ranks T test
B)Wilcoxon rank-sum test
C) $\chi$ ² test for independence
D) $\chi$ ² goodness-of-fit test

Question 35

Chi-square is calculated by summing the [(_____ -_____)² divided by _____].

A)observed; expected; observed
B)expected; observed; observed
C)observed; expected; expected
D)observed; observed; expected

Question 36

The $\chi$ ² test of independence is used with _____ data.

A)continuous
B)categorical
C)ordinal
D)quantitative

Question 37

Nonparametric is to parametric as _____ is to _____.

A)t-test; z-test
B)z-test; t-test
C) $\chi$ ²-test; t-test
D)t-test; $\chi$ ²-test

Question 38

Which of the following is not an assumption of the Wilcoxon rank-sum test?

A)The data are ratio,interval,or ordinal in scale-all of which must be converted to ranked (ordinal)data before conducting the test.
B)The underlying distribution is not normal.
C)The observations are independent.
D)There is homogeneity of variance.

Question 39

The calculation of the df for the $\chi$ ² test of independence is

A)r x c - 1.
B)(r-1)(c-1).
C)(r-c)n.
D)r x c.