In a multilevel model, which covariance structure is described as having zero covariances and heterogeneous variances?

In a multilevel model, which covariance structure is described as having zero covariances and heterogeneous variances?

• A. Diagonal covariance structure
• B. Difference contrast
• C. Direct oblimin
• D. Diagonal

Answer: (D)

In a multilevel model, a diagonal covariance structure means all off-diagonal elements are zero, so there are zero covariances between different observations. At the same time, the variances on the diagonal can differ, giving heterogeneous (different) variances for each observation or unit. This combination—zero covariances with varying variances—is exactly what the descriptor describes. The other options refer to coding schemes or methods used in different contexts (contrast coding or factor analysis rotation), not to a covariance pattern, so they don’t fit the description of zero covariances and heterogeneous variances.

In a multilevel model, a diagonal covariance structure means all off-diagonal elements are zero, so there are zero covariances between different observations. At the same time, the variances on the diagonal can differ, giving heterogeneous (different) variances for each observation or unit. This combination—zero covariances with varying variances—is exactly what the descriptor describes. The other options refer to coding schemes or methods used in different contexts (contrast coding or factor analysis rotation), not to a covariance pattern, so they don’t fit the description of zero covariances and heterogeneous variances.