Pioneer54: I expect we'll disagree on this one. First of all, as someone who's been a software engineer for 30 years, I can assure you this would be remarkably easy to implement. I believe if someone is intelligent enough to use this site and play games, they'll very easily understand it. And there'd be no implicit penalty of anyone who kept playing a game, whether they came to the site earlier or later. And I've spoken to plenty of people here who do believe that inactivity is a justification for demoting ratings. (Personally I couldn't care less, but this is a solution to what seems to be a significant problem for many.) Ratings are indeed an inexact science, a fact mirrored by Fencer apparently using an extremely simple lookup table to calculate them.

Jason: I only play two games here at the moment, but I have a habit of playing a game, say chess, for two years and then giving it up for another five years, then playing it again and leaving it again. Whatever the exact time period, I'm always away from a game for longer than I'm with it. It would give me a similar effect to the one you suggest. I'd build up a rating and then it would decay a long way. But I'd be prepared to take that hit on my rating. It would be my choice. And many have told me they would think it fairer if ratings like that did slip while people were away. On the other hand, I do believe your point about 'concentrated' players doing better than 'dispersed' players is a lot more valid than any of Pioneer54's, and it would be the only reason of those mentioned so far that think I would support against my own proposed solution.