Correlation coefficiencies of the antibody titers between different virus isolates used in the HI test. StrengellMari IkonenNiina ZieglerThedi JulkunenIlkka 2011 <p>The Pearson product moment correlation coefficients (r) were calculated for all pairs for 2009–10 viruses (panel A) and for 2010–11 viruses (panel B). All correlation coefficients were significant (p<0.01). C) The scatter plots and trend lines of antibody titers for each Finnish A(H1N1)2009 virus compared to the A/California/07/2009 vaccine virus.</p>