Exam 3 Quizzes

A researcher compares the mean difference between two groups with 15 students in each group and reports the following result for a two-independent sample t-test: t(29) = 3.52, p < .05. If this is a two-tailed test at a .05 level of significance, then what MUST be incorrect with this result? a. the degrees of freedom b. the value of the test statistic c. the level of significance d. the p value

a. the degrees of freedom

What are the degrees of freedom numerator for a study with n = 12 in each of four groups? a. 3 b. 4 c. 32 d. 36

a. 3

The t-statistic is an inferential statistic used to determine the number of standard deviations in a t-distribution that a sample mean deviates from: a. a t-statistic stated in the null hypothesis b. a population mean or mean difference stated in the null hypothesis c. a sample mean value or mean difference stated in the null hypothesis d. the sample standard deviation

b, a population mean or mean difference stated in the null hypothesis

How many interactions are possible in a two-way between-subjects ANOVA? a. 0 b. 1 c. 2 d. 3

b. 1

A source of variation associated with the variance of group means across the combination of levels of two factors is called a(n): a. main effect b. interaction c. cell mean d. two-way effect

b. interaction

A researcher computes the following one-way between-subjects ANOVA table for a study where k = 4 and n = 12. State the decision at a .05 level of significance. (Hint: complete the table first.) Source of Varation. SS. df. MS. F Between groups. 120. Within groups (error) Total 780 a. reject the null b. retail the null c. not enough information

b. retail the null

Homogeneity of variance refers to the assumption that: a. data in the population or populations being sampled from are normally distributed b. the variance of scores in each population is equal c. the probabilities of each measured outcome in a study are independent d. the data were selected using a random sampling procedure

b. the variance of scores in each population is equal

Simple main effect tests are necessary to analyze: a. a significant main effect b. a significant interaction c. any significant effect d. the results of a one-way ANOVA

b. a significant interaction

A researcher conducts a one-independent sample t-test with a sample of 12 participants. What are the degrees of freedom for this hypothesis test? a. 10 b. 11 c. 12 d. 13

b. 11

The table shows the group means for a two-way ANOVA. Which group means in the table would be analyzed using simple main effect tests? A1. A2 B1 4. 8 6 B2 10. 2 6 7. 5. a. 6 and 6 b. 7 and 5 c. 6, 6, 7, and 5 d. 4, 8, 10, 2

b. 7 and 5

Why does the t-distribution have greater variability in the tails of the distribution compared to a normal distribution? a. because the t-distribution is positively skewed b. because the sample variance is substituted for the population variance to estimate the standard error in this distribution c. because the normal distribution is negative skewed compared to the t-distribution d. it does not; the t-distribution is the same as a normal distribution

b. because the sample variance is substituted for the population variance to estimate the standard error in this distribution

What is the primary difference between a z-test and a t-test? a. the population variance is known in a t-test b. the population variance is unknown in a t-test c. the sample variance is known in a t-test d. the sample variance is unknown in a t-test

b. the population variance is unknown in a t-test

A researcher computes a significant one-way between-subjects ANOVA with eight participants in each of four groups and MSw = 18.1 and dfw = 30. What is the critical value for Tukey's HSD at a .05 level of significance for each pairwise comparison? a. 6.7 b. 5.3 c. 5.8 d. 4.4

c. 5.8

A main effect is a source of variation associated with mean differences: a. in the cell means given in a table summary b. across the combination of levels of two factors c. across the levels of a single factor d. across the combination of levels of two or more factors

c. across the levels of a single factor

Which of the following is a source of variation in the one-way between-subjects ANOVA? a. within-subjects variation b. between-subjects variation c. between-groups variation d. both b and c

c. between-groups variation

When researchers plotted the cell means of their data, they found that the lines of the graph crossed. This means that they likely found a: a. main effect of Factor A b. main effect of Factor B c. interaction

c. interaction

The two-way ANOVA differs from the one-way ANOVA in that: a. the two-way ANOVA is used when we observe more than two groups b. the one-way ANOVA is used when we observe the levels of two factors c. the two-way ANVOA is used when we observe the levels of two factors d. the one-way ANOVA is used when we observe more than two groups

c. the two-way ANVOA is used when we observe the levels of two factors

In a two-way between-subjects ANOVA, which effect is potentially the most informative when it is significant? a. the main effect of Factor A b. the main effect of Factor B c. the interaction

c. the interaction

The one-way between-subjects ANOVA is used when different participants are assigned to group(s). a. one b. two c. two or more d. zero

c. two or more

The two-independent sample t-test can be only computed when: a. the same participants are repeatedly observed in a group b. the sample is selected from a population with a known variance c. the size of the sample is larger than the size of the population d. different participants are observed one time in each group

d, different participants are observed one time in each group

To report the results of a t-test, which of the following is not reported? a. the test statistic b. the p value c. the degrees of freedom d. the critical values

d, the critical values

A researcher reports the following result for a t-test at a .05 level of significance: t(40) = 3.02, p < .05. Is this result significant? a. no, the p value is less than 5% b. yes, but only for a one-independent sample t-test c. yes, but only for a two-independent sample t-test d. yes, for both a one- or a two-independent sample t-test

d, yes, for both a one- or a two-independent sample t-test

A researcher conducts a two-independent sample t-test. What are the critical values for a two-tailed hypothesis test at a .05 level of significance when n = 14 participants in each group? a. +2.179 and -2.179 b. +2.145 and -2.145 c. +2.048 and -2.048 d. +2.056 and -2.056

d. +2.056 and -2.056

The table shows the group means for a two-way ANOVA. Which group means in the table would be analyzed for a main effect of Factor A? A1. A2 B1 4. 2 6 B2 10. 2. 6 7. 5 a. 6 and 6 b. 7 and 5 c. 4 and 8 d. 10 and 2

d. 10 and 2

In a two-way between subjects ANOVA, how many total sources of variation are there? a. 1 b. 2 c. 3 d. 4

d. 4

A researcher reports that emotional responses varied by the type of stressor in a controlled environment, F(4, 55) = 6.01, p < .05. How many participants were observed in this study? a. 12 b. 55 c. 59 d. 60

d. 60

The source of variation that cannot be attributed to or caused by having different groups is called: a. within-groups variation b. error variation c. between-groups variation d. both a and b

d. both a and b

A researcher reports that alertness in the classroom varies by the intensity of lighting in the room, F(3, 36) = 3.96, p < .05. How many light intensity groups were observed in this study? a. 1 b. 2 c. 3 d. 4

d. 4

What is the critical value for a study with n = 12 in each of two groups at a .05 level of significance? a. 3.89 b. 3.40 c. 4.28 d. 4.30

d. 4.30

In a sample of 26 participants, a researcher reports the following result for a one-independent sample t-test: t(25) = 1.907, p < .05. If this is a two-tailed test at a .05 level of significance, then what MUST be incorrect with this result? a. the degrees of freedom b. the critical value c. the level of significance d. the p value

d. the p value