EXAM 3
If the experiment-wise alpha for four tests is .05, then what is the value for test-wise alpha?
.01
If r = 0.75 and n = 15, then what is the value of?
3.84
Among the post hoc tests _________________ is too conservative when the number of pairwise comparisons is greater than three.
Bonferroni test
An ____________ is a measure of how cell means at each level of one factor change across the levels of a second factor
Interaction
What is the problem with the following data for computing a correlation?
The correlation coefficient will equal 0 because the variances and covariance will equal 0.
Participants in a study were assigned to groups based on their year in college (sophomore, junior, senior) and gender (male, female). What type of factorial design is most appropriate for this study?
a between-subjects factorial design
A researcher records the throwing distances for 12 participants in each of four different environments. If the throwing distances for the same participants are recorded in each environment, what type of statistical design is most appropriate for this study?
a one-way within subjects
Covariance refers to the extent to which the values of two factors
vary together
Omega-squared
A measure of the variability explained by the levels of a factor, divided by the total variability observed. It also corrects for the number of groups and the size of error in an ANOVA test. This estimate has two advantages over eta-squared: 1. It corrects for the size of error by including MSE in the formula. 2. It corrects for the number of groups by including the degrees of freedom between groups (dfBG) in the formula.
The phi correlation coefficient is used to measure the correlation between two nominal variables.
True
For a one-way between-subjects ANOVA, a study with 2 and 36 degrees of freedom, the degrees of freedom for the denominator is 38.
False
Tukey's HSD test
A test that allows you to compute a single value that determines the minimum difference between treatment means that is necessary for significance. A commonly used post hoc test. This test is more conservative than Fisher's LSD test in that the critical values are larger for each pairwise comparison.
Homoscedasticity is the assumption that there is an unequal variance of data points dispersed along the regression line.
False
If = 4 and = 16, then 4 groups must have been included in the study.
False
The point-biserial correlation coefficient is used to measure the correlation between two continuous variables.
False
A researcher computes a 2 × 3 between-subjects ANOVA and graphs the cell means, with levels of Factor A on the x-axis and levels of Factor B on the Y-axis. The lines obtained are parallel, indicating
No significant interaction
A researcher computes the following one-way between-subjects ANOVA table. State the decision at a .05 level of significance. (Hint: Complete the table first.) Source of Variation SS df MS F Between groups 50 5Within groups (error) 45 Total 140
Reject the null hypothesis
A researcher computes the following one-way within-subjects ANOVA table. State the decision at a .05 level of significance. Source of Variation SSdfMSBetween groups 30Between persons 6Within groups (error. 64 Total 13
Reject the null hypothesis.
A researcher has 7 participants rate the effectiveness of a peer-mentoring program. Each participant rated before, during and after the program. What is the critical value at .05 level of significance?
3.89
A researcher observed the behavior of 5 bonobo apes in five different social conditions. What are the degrees of freedom between-groups for a one-way within-subjects ANOVA?
4
A researcher measures the following correlation: r = -0.6. What is the value of the coefficient of determination?
.36
R2 is a more powerful estimate of effect size than Eta-squared.
False
There are two factors and four cells in a 3 × 4 between-subjects ANOVA.
False
Using the two-way mixed ANOVA, different participants are observed at each level of the between-subjects factor.
False
If a study has 16 groups, then it is possible that the degrees of freedom for each factor are 3 and 3 for a two-way between-subjects ANOVA.
True
Bonferroni test
a post hoc test that provides a more strict critical value for every comparison of means. procedure adjusts the alpha level, or probability of committing a Type I error, for each test. The alpha level for each test is called testwise alpha. We use the Bonferroni procedure to find testwise alpha. To find testwise alpha, we divide experimentwise alpha by the total number of pairwise comparisons made.
Fisher's LSD test
called the protected t test, is the most liberal post hoc test allowed in published research studies. It has the lowest critical values acceptable, which increases the power to detect an effect or mean difference between two groups. Also, this test does not require that the number of participants in each group is equal.
The assumption that the best way to describe a pattern of data is using a straight line is
linearity
All post hoc tests control for Type II error.
False
A _______________ is a statistical procedure used to describe the strength and direction of the linear relationship between two factors
correlation
The Spearman correlation coefficient is used to measure the correlation between two ordinal variables.
True
A researcher measures the relationship between amount of protein intake and time on cognitive tasks. If SSxy = -320 and ssx = 360, and ssy = 450, then what is the value of the correlation coefficient?
- .079
The Bonferroni test is an appropriate post hoc test following a significant one-way within-subjects ANOVA because a related samples t-test can be calculated on the data
True
Two research studies on the effectiveness of a training program revealed the following results: the sum of squares between groups was larger in Study 1 than in Study 2; the sum of squares total is smaller in Study 1 than in Study 2. Using eta-squared, in which study will the effect size be larger?
Study 1
A researcher groups college students in a study based on their year in college (junior, senior) and their major in college (engineering, arts, sciences). He concludes that perceptions of college life are more positive among seniors majoring in the arts. To reach this conclusion, which statistical test would need to be computed?
all of the above
The error variation in a within-subjects ANOVA is split, and the ________________ is removed as a source of error from the denominator of the statistic.
between-persons variation
Observing different participants one time in each group is referred to as
between-subjects
A researcher records the amount of time spent by male and female college students on a computer vs. playing a sport. Different participants were observed in each group. What type of statistical design is appropriate for this study?
two-way between-subjects ANOVA
Chi-square test
A significance test used to determine if a linear relationship exists between two variables measured on interval or ratio scales.
A researcher compares differences in response to shock among rats given an electric stimulation of 1, 3, and 5 volts. If she observes 20 rats in each group, then what are the degrees of freedom for the one-way between-subjects ANOVA?
(2, 57)
The degrees of freedom for within groups, or error dfE in a one-way within-subjects ANOVA is given by:
(k-1) (n-1
A researcher measures the correlation in rankings for ice cream flavors and consumers' rankings of their favorite flavors. If = 19.5 and n = 8, then what is the value of the correlation coefficient?
.79
A researcher reported the following results for a one-way between-subjects ANOVA: F (2,27) = 3.42, p < .05, = .12. How many participants were observed in this study?
30
The factorial design is a research design in which participants are observed
across the combination of levels of two or more factors.
A researcher observes the same group of children in their home environment, in their preschool, and in the lab. Which source of variation is the variability attributed to observing the same participants in all three settings?
between-persons variablity
Computing a one-way between-subjects ANOVA is not appropriate when
the same participants are observed in each of two or more groups for one factor
The following results is reported for a one-way within-subjects ANOVA: F(2, 27) = 4.55, p < .05 ( = 0.33). Which value in the summary cannot be correct?
the test statistic
A one-way between-subjects ANOVA is conducted to test for mean differences between the levels of one factor.
true
There are two sources of variation in a one-way between-subjects ANOVA: one attributed to differences between groups and one attributed to factor.
False
When subjects are not responding consistently, the one-way within-subjects ANOVA can actually have more power to detect an effect than the one-way between-subjects ANOVA.
False
The sum of squares within-groups and sum of squares between-groups are both sources of error.
True
Eta-squared
When this measure is used with the ANOVA, 22the symbol R may be used instead of η . Eta-squared is computed as the sum of squares between groups divided by the sum of squares total: R 2 = η 2 = S S BG S S T . Observed power is a type of post hoc or retrospective power analysis that is used to estimate the likelihood of detecting a population effect, assuming that the observed results in a study reflect a true effect in the population. Eta-squared is often reported as R2 for an analysis of variance test.
Partial omega-squared is a more conservative estimate of effect size than omega-squared because
it corrects for the size of error by including MSE in the formula
The number of levels of the factor in a study is indicated by
k
There are ____ cells or groups in a 2 × 4 ANOVA design.
8
Unlike eta-squared, the formula for omega-squared corrects for the number of groups and the size of error in its estimate of effect size.
True
Which of the following is a post hoc test for a one-way between-subjects ANOVA?
Turkey's HSD test
When the variability attributed to between-groups is less than the variability attributed to error, then the value of the test statistic for a one-way between-subjects ANOVA is
Not significant.
Partial estimates of proportion of variance are used for a one-way within-subjects ANOVA.
True
A researcher computes a 3 × 3 between-subjects ANOVA in which 8 participants are observed in each cell. What are the degrees of freedom error for this study?
63
The coefficient of determination is the square of the correlation coefficient.
True
The mean square is the same as a variance since it is SS divided by the degrees of freedom.
True
The correlation coefficient ranges from -1.0 to +1.0, with values closer to ±0.0 indicating
that two factors are less likely to be related
