Correlation between the reduced antigenicity of HP9 and the increased antigenicity of HM1 in HSQ-immunized hemophilia A mice. Ratios of assay titers for HSQ to HP9 and for HM1 to MSQ from the experiment shown in Figure 2 were calculated and plotted. The regression line corresponds to a coefficient of correlation, r, of 0.61, which is significantly greater than 0 (P = .001; t test).