Which of the following is not a good reason for performing a

Which of the following is not a good reason for performing an analysis of covariance?

a. a desire to take account of a known relationship between covariate and the dependent variable

b. a desire to remove statistically some individual differences among individuals.

c. a desire to examine the relation amoung the covariates.

d. none of the above--all are good reasons for performing an analysis of covariance.

Solution

Answer is option D

Analysis of covariance (ANCOVA) is a general linear model which blends ANOVA and regression. ANCOVA evaluates whether population means of a dependent variable (DV) are equal across levels of a categorical independent variable (IV) often called a treatment, while statistically controlling for the effects of other continuous variables that are not of primary interest, known as covariates (CV) or nuisance variables. Mathematically, ANCOVA decomposes the variance in the DV into variance explained by the CV(s), variance explained by the categorical IV, and residual variance. Intuitively, ANCOVA can be thought of as \'adjusting\' the DV by the group means of the CV(s)