Efficacious End User Measures—Part 1: Relative Class Size and End User Problem Domains
Figure 8
Instead of the optimum value being maxima, like the other measures evaluated, the optimum DOR value is a minimum. Hence, the contours show a valley instead of a ridge. Also contrary to the other measures, DOR decreases when the absolute class size effect becomes noticeable. This means that the contours are closed, instead of open like the others. DOR’s vertical optimum boundary line and constant value (seen in Figure 8(b)) indicate that DOR (and hence, DP) is rCS-invariant. DOR/DP optimum boundaries (approx. 1.2) are offset from the optimum boundaries seen in the other rCS-invariant measures (approx. 1.4). DP, the log form of DOR, has the same characteristics as DOR.
(a) Contour graph of rCS versus boundary versus DOR value. Scaling makes the measure seem somewhat rCS sensitive. However, Figure 8(b) shows DOR is actually rCS invariant
