user142: I've been impressed with the way the Glicko rating system works. In particular:

more games played recently cause your rating to stabilize
fewer games played recently cause your rating to fluctuate until you get several recent games under your belt

USCF modified their system to be similar a few years back (where there is a sliding scale to amplify or dampen the rating change for a given match), and now that Glickman (the inventor of Glicko) is on the rating board for the USCF, I imagine they'll eventually adopt an even more flexible system, like his own.
Is there a reason (other than being resistant to change, or that they just haven't gotten around to it yet) that FIDE doesn't adopt a more accurate rating system? 

user94: As far as I understand the Glicko rating system adds a reliability score to the rating number, which may provide a higher fairness regarding the rating score adjustment calculations. Obviously this might lead to the wrong assumption that there is a correlation between playing rated games and resulting playing strength (since not playing decreases the reliability score which in turns de-valuates your rating number somehow). I see a lot of problems connected to the reliability score, although I must admit I am no expert about the subtleties of the system. Just to pick three:

A player playing only the rare rated game might get no invitations anymore.  Imagine you are a tournament director inviting attractive players. Now you have to choose between 10 players, all of which have the same rating number, but different reliability numbers. Probably you will pick the ones with the best reliability numbers first. Over time the reliability gap between players with many rated games and less ones might widen.
Manipulation of rating numbers might become easier. Even the ELO system is not cheat-safe, because some people got ratings or IM/GM norms by playing in rigged tournaments. A good reliability score might make helping players with no reliability score very cheap - the good player gives rating points without losing much himself. As soon as money is involved, being cheat-safe is an important issues. I have the feeling the Glicko rating system is more prone to manipulations.
The communication and understanding of playing strength might become more difficult to the masses. When you communicate a ranking list, you run into problems. A player with a rating of 2000-50 has a "real playing strength" somewhere between 1900 and 2100. Another player has got 1950-2000, which translates to a number in the range of 1750 and 2150. So the player with 1950-2000 might be in fact the better player, but will probably be ranked below the other one, only because he played less games or against less reliable opponents. You make explaining your ranking system more difficult to people, without really guaranteeing more fairness. A GM which stops playing might gain "potential strength" and boast about his world champion potential, because his reliability number makes increasing room for deviation (mind it: in both directions, not only downwards!).

To sum it up: You might get more than you bargained for, because the whole package does not only come with improvements. And since there are heavy monetary issues involved when you look at the upper end of the ranking lists, I do not see the merits of changing an existing system.

user70: It is not proven that Glicko is more accurate.  Glicko just solves the problem a different way, with a different emphasis.  Consider that all these systems abstract a human mind to a 4 digit number.
There's a lot of politics in ratings; it's a touchy subject.  If FIDE were to adopt it, they'd produce a new top-100 list, and a lot of GMs would likely be upset.
The ELO system is very easy to understand; transparency is important.  More complex systems have immediate disadvantages.

142: <p>I've been impressed with the way the <a href="http://glicko.net/glicko.html">Glicko</a> rating system works. In particular:</p>

<ul>
<li>more games played recently cause your rating to stabilize</li>
<li>fewer games played recently cause your rating to fluctuate until you get several recent games under your belt</li>
</ul>

<p>USCF modified their system to be similar a few years back (where there is a sliding scale to amplify or dampen the rating change for a given match), and now that Glickman (the inventor of Glicko) is on the rating board for the USCF, I imagine they'll eventually adopt an even more flexible system, like his own.</p>

<p>Is there a reason (other than being resistant to change, or that they just haven't gotten around to it yet) that FIDE doesn't adopt a more accurate rating system? </p>
 94: <p>As far as I understand the Glicko rating system adds a reliability score to the rating number, which may provide a higher fairness regarding the rating score adjustment calculations. Obviously this might lead to the wrong assumption that there is a correlation between playing rated games and resulting playing strength (since not playing decreases the reliability score which in turns de-valuates your rating number somehow). I see a lot of problems connected to the reliability score, although I must admit I am no expert about the subtleties of the system. Just to pick three:</p>

<ul>
<li>A player playing only the rare rated game might get no invitations anymore.  Imagine you are a tournament director inviting attractive players. Now you have to choose between 10 players, all of which have the same rating number, but different reliability numbers. Probably you will pick the ones with the best reliability numbers first. Over time the reliability gap between players with many rated games and less ones might widen.</li>
<li>Manipulation of rating numbers might become easier. Even the ELO system is not cheat-safe, because some people got ratings or IM/GM norms by playing in rigged tournaments. A good reliability score might make helping players with no reliability score very cheap - the good player gives rating points without losing much himself. As soon as money is involved, being cheat-safe is an important issues. I have the feeling the Glicko rating system is more prone to manipulations.</li>
<li>The communication and understanding of playing strength might become more difficult to the masses. When you communicate a ranking list, you run into problems. A player with a rating of 2000-50 has a "real playing strength" somewhere between 1900 and 2100. Another player has got 1950-2000, which translates to a number in the range of 1750 and 2150. So the player with 1950-2000 might be in fact the better player, but will probably be ranked below the other one, only because he played less games or against less reliable opponents. You make explaining your ranking system more difficult to people, without really guaranteeing more fairness. A GM which stops playing might gain "potential strength" and boast about his world champion potential, because his reliability number makes increasing room for deviation (mind it: in both directions, not only downwards!).</li>
</ul>

<p>To sum it up: You might get more than you bargained for, because the whole package does not only come with improvements. And since there are heavy monetary issues involved when you look at the upper end of the ranking lists, I do not see the merits of changing an existing system.</p>
 70: <p>It is not proven that Glicko is more accurate.  Glicko just solves the problem a different way, with a different emphasis.  Consider that all these systems abstract a human mind to a 4 digit number.</p>

<p>There's a lot of politics in ratings; it's a touchy subject.  If FIDE were to adopt it, they'd produce a new top-100 list, and a lot of GMs would likely be upset.</p>

<p>The ELO system is very easy to understand; transparency is important.  More complex systems have immediate disadvantages.</p>
