Model functions


mv is used to estimate missing values in the response variable. Formally this creates a model term with a column for each missing value. Each column contains zeros except for a solitary -1 in the record containing the corresponding missing value.

The equations for mv and any terms that follow are always included in the sparse set of equations.

Missing values are handled in three possible ways during analysis. In the simplest case, records containing missing values in the response variable are deleted. For multivariate (including some repeated measures) analysis, records with missing values are not deleted but ASReml drops the missing observation and uses the appropriate unstructured R-inverse matrix. For regular spatial analysis, we prefer to retain separability and therefore estimate the missing value(s) by including the special term mv in the model.

Return to start