Model Dimension

The fixed and random effects for this model are identical to those from the First-Order Autoregressive model. The First-Order Autoregressive covariance structure is replaced with an Unstructured one, which requires 10 parameters -- 8 more than the First-Order Autoregressive. This covariance structure is again applied to the levels of LOCID*MARKETID, independently for each of the 133 store locations in the study.