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. 2015 Apr 22;15:174. doi: 10.1186/s12913-015-0834-z

Table 1.

Study group sizes and balance metrics before and after matching using CEM

Study group Treatment Comparison CEM L1 metric*
Before CEM match 34,282 4,965 29,317 0.2072
After CEM match 33,468 4,948 28,520 3.57 E−15
Members lost due to match 814 17 797

*L1 metric is an indicator of balance/equivalence between study groups. A value of 1 indicates complete dissimilarity (no overlap) and a value of 0 indicates groups are perfectly equivalent or balanced.