Will add a note to this to add to the importance of each person active at a single time. You don't just contribute a single dot. You contribute two dots for every other person logged in 100 people logged in gives 9901 dots - 101 people logged in gives 1101 dots. So please remain active as long as possible as often as possible. Edit: image sampling at every 5 minutes might miss some stuff if this is indeed the case - for example if 100 people are on at t-2.5 minutes and then at t + 1 minute 100 new people log in but at t + 5 minutes (sample period) the first 100 people have all dropped we would have missed the giant activity between those two groups of people. This is an extreme case and since most of the people active are nearly constantly active we are not likely to miss much data between samples at the current time.