IMPORTANT: New problem selection algorithm

[richard]

Hi all,

In the next few hours I will be putting in place an improved problem selection algorithm.  The new algorithm will ensure a more predictable selection around the user's current rating.  It will also ensure that when forced to choose problems the user has seen before, it will choose a problem that has been seen least recently.

The algorithm may need to be tweaked slightly over time as I'm not sure if the current spread is too narrow or too wide (but it should at least be centered on the user's rating, unlike the last selection algorithm).

The down side of the new algorithm is that it is likely to cause a bit of a shakeup in the ratings. This is likely to be most noticeable at the higher and lower ends of the rating ranges.  Users at the extreme ends will have got used to seeing problems which are quite often much closer to the average problem rating than their current user rating would suggest.  This means that very lowly rated users will start getting easier problems from now on and the highest rated players will start getting harder problems.

Whilst this may lead to some short term rating adjustments (and rating related rage), I'm confident that overall this will lead to a more appropriate matching of problem and user.

For those that experience a rating drop at the high end (and this is not necessarily going to be the outcome, users also gain more points when they get higher rated problems correct), please try not to worry too much and about ranking drops.  While some users may be able to avoid dropping in the short term by not doing any tactics, eventually their increasing RDs will lead them to be inactive and they will drop out of the rankings altogether.

Regards,
Richard.