Hi Don
There are four set of stats listed for every user on 500px, the first is an activity stat, the next is the faved stat (total number of pics marked favourite by visitors), then the photos stat (the total number of pics uploaded by that person), then finally the rating stat (the total number of likes received for all pics uploaded). The activity stat does not seem to relate to the popularity of a person's portfolio, nor to the number of photos uploaded, or even the traffic that comment or even just look. I noticed that Nic has zero activity shown on his stats which makes me think the stats is more to do with the activities of the person to whom the portfolio belongs (Nic said he doesn't use 500px anymore) ... but what activities is it registering?