Correlation histogram for a) FD magnitude, |FD|, versus IMF magnitude, B; b) |FD| versus solar wind speed, v_rel; c) the product of the FD magnitude and duration, |FD|t_FD, versus the product of the magnetic field enhancement and duration, Bt_B. The y-axis represents the number of correlations in specific correlation coefficient class (x-axis). Each histogram is based on one million calculated correlation coefficients.