Mutual Information. Mutual Information (MI) is a measure of the strength of the relationship between two nodes. By computing the MI for eruptive outcome with each observable, it is possible to identify which parameters provide the greatest information about future activity. The black diamonds denote the mean MI % estimate. Boxes denote the median (centreline), first and third quantiles. The whiskers on the plot denote the 5th and 95th percentiles. The data are provided in Additional file 7.