Continuity Measure Our primary predictor variable was an index of COC. Several such indices have been developed.21–23 We opted to use the COC index developed by Bice and Boxerman23 that is derived from Rae and Taylor's index of fragmentation24 and is of the general form:COC=∑j=1s nj2−NN(N−1)where N = total number of visits n = number of visits to providerjs = number of providers The COC takes on..