The Two Anchors of a Measure

A quantity appears in three forms, one in each of the three worlds of analytical data. In the Business World it is a concept, a name with a meaning and no anchor. In the Material Data World it is a metric, a number stored or shown at one anchor. In the Data World it is a measure, which needs two: the anchor where its values stand and the anchor its last reduction takes values from. The canonical form of a measure, Op(m@A)@B, is the last edge of its derivation path and part of its identity. The one exception is a measure family, whose members can be written F@A.

Names carry meaning only in the Business World. In the Data World a measure's name is a handle for its identity, and in the Material Data World a metric's name is a label. What a name supplies at a crossing is its binding: a concept bound to a measure family needs only a first anchor, and any other binding must carry the second anchor, in its declaration or in the request. Binding a concept to a measure fixes the second anchor and closes the intent gap. Reading a metric as a measure requires its grain to be checked against the records and its second anchor to be recovered from its derivation, which closes the servability gap. Worked cases cover averages, minimum balance, month-end balance, weighted prices and distinct counts, and Frame-QL's anchor rules show how a request writes the second anchor.