Two-dimensional histograms (shades of red) of time lags and maximum correlations of nine couples of AIA channels for the 4451 event pixels of the HRI_EUV field of view. The estimated background has been subtracted. The green dashed lines are the confidence levels, derived in Appendix A. The ν₉₅ parameter quantifies the asymmetry of the time lag distributions. It represents the average of the event time lags above the 95% confidence level weighted by their respective maximum correlations.