SMM12 — Superclasses of RankingMeasureRelationship and GradeMeasureRelationship are inconsistent

The RankingMeasureRelationship and GradeMeasureRelationship fulfill similar roles in association of a RankingMeasure or GradeMeasure to their input Measure. The superclass of RankingMeasureRelationship is BaseMeasureRelationship which means that inline rescaling can be applied to its base measurements. The superclass of GradeMeasureRelationship is MeasureRelationship which does not provide inline rescaling.

The superclasses should be the same, either MeasureRelationship for both or BaseMeasureRelationship for both.

An argument for BaseMeasureRelationship for both can be seen with US temperatures and European temperatures. If one wants both to be graded as COLD, MODERATE or HOT, either the US temperatures (in Fahrenheit) or the European temperatures (in Celsius) would need to be rescaled. That is, the same grading intervals can be used for both Fahrenheit and Celius if the Fahrenheit is first rescaled to Celsius.

*Change super class of GradeMeasureRelationship *

Set the super class of GradeMeasureRelationship to be BaseMeasureRelationship. Modify Diagram 10.2 to include the generalization relation between GradeMeasureRelationship and BaseMeasureRelationship.