Roger:
If we consider just the hits, in the windows, which does NOT distinguish against the count of quakes, then we simply go on the ratio of hits to opportunities or A = 5/5 and B = 4/5 (although the browser I am using has the underlines misplaced)

However I cannot tell in the diagram whether or not the stacked asterisks for a date mean several quakes occurred or whether it is a cluster of quake which I would want to lump together into one event. I think if it is several quakes that occur during the day, you'd get an argument from most people that this IS significant, and has to also be considered in to the discussion.

1. Only consider hits?
2. Or consider hits + number of events per hit?

more discussion. I am very new at this so I expect I will be stumbling around awhile. (laugh)