achieves_planned_objective descriptive statistical calculation objective spread calculation data transformation variance calculation A variance calculation is a descriptive statistics calculation in which the variance is defined as the average squared distance of each observation in the data set to the mean of the data set. It is also known as the second central moment. From Monnie's file comments - need to add spread_calculation and moment_calculation roles but they don't exist yet - (editor note added by James Jan 2008) Monnie McGee PERSON: Monnie McGee variance calculation spread calculation objective descriptive statistical calculation data transformation metadata complete