If all departments have been located then the adjacency and efficiency of the graph are computed. To score the graph, the sum of all positive relationships between adjacent departments will be denoted by PA. The sum of all negative relationships between non-adjacent or separated departments will be denoted by NS. The sum of all positive relationships between non-adjacent or separated departments will be denote by PS, and the sum of all negative relationships between adjacent department will be denoted by NA. The adjacency (A) and efficiency (e) are then computed as
(4.14)
(4.15)
The efficiency has its numerator all relationships that are desirable, namely positive adjacent and negative separated ones. It has in the denominator the sum of all relationships. The efficiency is thus a measure of the quality of the adjacency graph with values between 0 and 1 and invariant with respect to the magnitude of the relationships. A diagram which maximizes the adjacency will also maximize the efficiency since the numerator of the efficiency is equal to adjacency minus the constant (NS + NA).