Using the adjusted values

6-3.2 Using the adjusted values.

The adjusted reliability and coincidence are associated with the particular combination of fields making up the comparison weight. Combinations (

) present in the constructive value dependence chain are also presence dependent. The equation 3.1 for blocking recall must use the adjusted presence and reliability, whose values are determined by the combination involved. The only valid combinations are those sub-chains all of whose fields are blocking or weighting fields. Some choices may result in the adjusted presence for a blocking field becoming very small or disappearing altogether. Although the choice may be valid, it may reduce recall drastically.

recall = ap_ki × ar_ki (6.9)

Similarly the equation 3.12 for the blocking precision uses the adjusted reliability and coincidence. Here, of course, precision only makes sense when the field is present. The measure is only for comparisons in blocks.

precision = {1+(G ÷ N_U)} ÷ {1 + (G ÷ N_U) + [(ac_ki ÷ ar_ki) × N_total]} (6.10)

The adjusted reliability enters into the probability that the comparison weight will be matched (y) of equation 6.4, and the adjusted coincidence, that the comparison weight will be unmatched (z) of equation 6.5.