5-3.6 Constructive value dependence.
There is also an obvious value dependence among
some of the personal name fields. Normally if we weight on the Name Code, we should not also
weight on the name spelling. Spellings may be grouped as variants of a name and assigned their
name group code on the basis of their spelling (usually by its outward form). After this grouping
process the variation among spellings within those having a particular code may be great or small.
The coincidence value of every name would measure differently, there likely being only a dozen
or so name variations for each particular code. This process is quite different from calculating the
coincidence value of a spelling as independent. In that case we simply estimate the independent
probability of choosing the same spelling from among all the variations in the test database, not just
those within a group. Constructive value dependence occurs when there is a full dependence of data
values in one field on specific values in certain other fields. The field value's very presence is also
dependent.
Another case of constructive value dependence arises when the meaning of the data in one
field is a derivation of data in another field. For example, in genealogy, references to localities are
to different jurisdictional levels, and each one may receive its code depending on its meaning. The
town of Coos Bay in Oregon may be coded like Marshfield, an earlier name for the same town. This
kind of grouping occurs with towns, counties, states, provinces, countries, etc., that may all be part
of the locality designation identifying the place of the event. The town is only in one county, the
county in one state, etc. The code, then, depends constructively on the locality.
