Deck 5: Analysis of Covariance

Question 1

Analysis of covariance (ANCOVA) mirrors the ordinary analysis of variance (ANOVA), but only before the effect of the covariate has been partialed out.

Answer 1

False

Question 2

The effects of the covariate are removed by adjusting the scores on the IV in order to reflect the initial differences on the covariate.

Answer 2

False

Question 3

The first major purpose for the use of ANCOVA is to increase the sensitivity of the F tests of main effects and interactions by reducing the error variance, primarily in experimental studies.

Answer 3

True

Question 4

The second major purpose for the use of ANCOVA involves a statistical adjustment procedure where the means of the DVs for each group are adjusted to where they would be if all groups had scored equally on the covariate.

Question 5

The third major purpose for the use of ANCOVA is to interpret differences in levels of the IV when several DVs are included in the analysis.

Question 6

One of the assumptions for ANCOVA is that the observations within each sample must be randomly sampled and must be dependent on one another.

Question 7

Another assumption is that the distribution of scores on the independent variables must have equal variances.

Question 8

An additional assumption of ANCOVA is that a linear relationship exists between the DVs and the covariate(s).

Question 9

ANCOVA assumptions also require that the regression slopes for a covariate are homogeneous.

Question 10

The sixth assumption for ANCOVA is that the covariate is reliable and is measured without error.

Question 11

The assumption of homogeneity of variances is best tested through the use of Levine's test.

Question 12

The assumption of linearity is more precisely tested by obtaining and examining residual plots between the covariates and the IVs.

Question 13

Regression is incorporated into ANCOVA in order to predict scores on the DV based on knowledge of scores on the covariate.

Question 14

A violation of the assumption of homogeneous regression slopes is crucial with respect to the validity of the results of ANCOVA.

Question 15

The null hypothesis being tested with the assumption of homogeneity of regression slopes is that all regression slopes are equal.

Question 16

The logic of ANCOVA is identical to the logic behind ANOVA.

Question 17

The initial phase of the analysis with ANCOVA involves the statistical adjustments of the DV group means in order to control for the effects of the covariate on the IVs.

Question 18

Interpretation of ANCOVA results is similar to that of ANOVA.

Question 19

If the F test of factor-covariate interaction is significant, then the full ANCOVA should not be conducted.

Question 20

If factor-covariate interaction is not significant, then one can proceed with interpreting the Levene's test as well as proceeding with the full ANCOVA.

Question 21

If the Levene's test is significant, then homogeneity of variance is assumed.

Question 22

Line graphs are typically created to graphically represent any interaction between/among covariates based upon the DV.

Question 23

ANCOVA adjusts group means as if participants scored equally on the covariates.

Question 24

F ratios and p values for each covariate indicate the degree to which the covariate significantly influences the DV.

Question 25

When the covariate adjustment is made, a portion of the treatment effect will be removed.

Question 26

The first step in interpreting the results of ANCOVA is to:

A) Determine if factor interaction is present by examining the F ratio and p value for interaction.
B) Obtain a measure of effect size.
C) Test the various combinations of levels for Factor A and Factor
D) Only (a) and (b) are correct.

Question 27

Eta squared in ANCOVA is interpreted as:

A) The proportion of variance in the DV explained by the IV(s) in the sample.
B) The proportion of variance in the covariate explained by the IV(s) in the sample.
C) The proportion of variance in the IV(s) in the sample after partialing out the effects of the covariate(s).
D) None of the above.

Question 28

A two-way ANCOVA tests the following three separate hypotheses simultaneously in one analysis:

A) Two of the hypotheses test the significance of the levels of the two IVs separately, after removing the effects of the covariate.
B) The third tests the significance of the interaction of the levels of the two IVs, also after removing the effects of the covariate.
C) The third tests the significance of the interaction of the levels of the IVs and DV after removing the effects of the covariate.
D) (a) and (b) are correct.

Question 29

Ideally, if quantitative variables are being used as covariates in ANCOVA, one should choose those variables that:

A) Are significantly correlated with the DV.
B) Have low correlations among themselves.
C) Have high correlations among themselves.
D) (a) and (b) are correct.

Question 30

If there exists a weak correlation between two covariates, they will remove relatively unique portions of the error variance from the DV, which is:

A) Advantageous.
B) Disadvantageous.
C) Of no consequence because the correlation is weak.
D) None of the above is correct.