Figure. Distribution of hepatitis C virus (HCV) enzyme immunoassay signal-to-cutoff (S/CO) values by recombinant immunoblot assay (RIBA) interpretations among HCV-RNA–positive [PCR (+)] and HCV-RNA–negative [PCR (−)] donated blood samples. Group a differs statistically from all groups b with 95% confidence intervals. The Mann-Whitney test was used to compare the 2 groups. (+), positive; (−), negative; (Ind), indeterminate. *S/CO values outside interquartile intervals; †Kruskal-Wallis test.