Figure 1: Comparison of Kova and improved Neubauer for sperm concentration measurement. A total of 60 different sperm concentrations were measured with the two methods. (a) Bland–Altman plot of difference in the concentration (106 ml−1) measured with Kova chamber and improved Neubauer hemocytometer against the mean of the 2 values (circles). The solid line represents the mean of differences. The dotted lines indicate the 95% confidence limits (mean ± 1.96 × s.d.). (b) Linear regression of the log-transformed concentrations (106 ml−1) estimated with Kova chamber 10 (y-axis) and improved Neubauer hemocytometer (x-axis). The solid line represents the Tessier's linear regression (XK = 0.95XN + 0.94).