Sean Hewitt wrote:E Michael White wrote:
I dont think its been mentioned before but Swiss events with an odd number of players also cause deflation and spread of grades, by small amounts which accumulate.
Hi Michael. That's interesting. Can you tell us why that is?
Hi Sean
The way I look at this is that in a swiss with an odd number of players, those that get the byes play one game less and are at the bottom end of the draw. If they played an extra game as in an even player swiss, they would also play someone at the bottom end. Either the player or their opponent would gain a significant amount on their TPR as the result % would increase. Changing 1 out of 4 to 1.5 out of 5 and leaving the average grade of opponents approximately the same changes their % from 25 to 30 giving a TPR increase of 5 ECF points. Nearly always these missed out results occur at the bottom end of the draw.
Its difficult to verify this numerically or analytically because the other elements of deflation/inflation can swamp it. I was only considering the built in effect of swiss events with byes allocated as they are. I think it would be a fair estimate to say the swiss effect is the same as considering the virtual grade changes on the same group of players assuming they all played the same number of games in a season before the event, as this removes activity based deflation/inflation.
Sean Hewitt wrote:E Michael White wrote:
Some baby boomers born 1945-1950 seem to be returning to play more chess; this is likely to have a short term inflationary effect and may make the current grading fix look more effective than it is in curing deflation.
Can you tell me why this is likely to be inflationary? I can't figure it out this early in the morning!
Here I was thinking that a group of players may start playing again; I have noticed some old names/faces reappearing. The new player process reintroduces players at a more realistic level on average although as someone posted recently apparent anomalies can occur. I guess that that group of players will gradually reduce in grade causing the grades of opponents to rise. If they are particularly active then this will magnify the effect. They don’t have to be very strong players just more active and gradually reducing in strength. Comparing this to the last 5 years, there were fewer players born in the period 1940-1945.
Roger de Coverly wrote:Could you expand this? We know that more active players have a higher average grade than less active players. An obvious conclusion is that if you play a lot, then you get better. I don't think that players playing 5 games a year have much impact on those playing 30 or much more
both
because you are less likely to meet them in an event ( because they don't play much)
and
Because the effect of one individual game is reduced for the more active players.
I think Jack’s explanation is correct. I would add that I believe that the average number of games played is less than 20 so the figures for distortion in one game could be an extra 1 to the winner and -5 to the loser.
Roger de Coverly wrote:
More to the point is that the active players mostly play each other, so it doesn't have much effect on the most active players as to what grade the inactive players (5 a year) have.
The most important point is how many games are played where the opponent activity rates are significantly difference. Deflation/inflation emerges on a per game basis and accumulates over the years. Many players who play mostly in their local league support their local congress and not many others. If you as an active player play in those congresses you will meet them although mostly you might expect to meet active players. Last time I looked the average number of games played was just under 20, A graded players counted for only 20% and A,B and C accounted for 50-60%. Those figures suggest to me that there will be many games where a 16 game player plays against a 32 or more game player but without data this cannot be checked.
Brian Valentine wrote: The point is that if both players repeat their activity the next year Jack will contribute 100*.5 points = 50 into the rating pool to be redistributed by results, whereas his opponent will place 50*1 points =50 into the pool. Hence deflation explained by this idea only occurs if activity alters.
Except that we are assuming Jack improves so the reverse does not compensate for distortion.
Bear in mind to cause activity based deflation you do not need to be a very strong player just more active and improving. The link between activity and improvement is intuitively appealing. Some studies have been done to show that the effect is not great but in my view the wrong correlation was looked at. Although activity v player improvement is easier to understand the correlation should be based on games not players. ie the correlation needs to be evaluated between games played by active players versus improvement in strength of the players who played those games thus weighting by games.
Roger de Coverly wrote:Do you have an opinion about changes in skill standards? Take two players who were about equal graded in the 1970s. One retired then and has recently returned but hasn't updated their knowledge. The other has played continuously. Do you think they will both have about the same grade playing today?
If you had asked my that in 1965 I would have said a player could have expected to be initially about 30 points lower in playing strength unless they had previously been very strong ie 215 +. But now I am inclined to think about 15 points initially. I know there are players who have played continuously and dropped by similar or greater amounts but there are also players who are not much lower than before they stopped.
I know different players will record different experience but what seems to me to happen is that predominantly combinative players lose their skill quicker after age 55-60 which would coincide on average with reduction of short term memory skills. Whereas a predominantly positional player utilises more stable longer term memory.
Many say that the opening theory and preparation has advanced so much that a returning player doesn’t have a chance. But those reasons equally favour a returning player as it much easier to look at databases and play on the internet before making a return. In addition a player can wheel out 1960s theory and update it to the confusion of their opponents. Some of the lines I gave up as unsound 30 years ago I have discovered with Fritz 12 are playable, are not in the books and can lead to advantage.