IsaVulpes wrote on 06/22/17 at 11:19:09:


Good points all around by Isa and Eric, IMO

Maybe those were theoretically significant games.

TopNotch wrote on 06/27/17 at 03:57:05:
 
Also, the notion of an objective assessment of a position falls apart if you try to make it  too precise. Mathematically, there are three possible assessments--absolutely won, absolutely lost, or absolutely drawn. The rest, including the whole apparatus of "slightly better," etc., exclusively concerns the flaws of imperfect players. So "easier to play" and "objectively better" blur into each other. And, of course, different imperfect players have different flaws! Authors doing a good job will disagree a little.

So if Watson evaluates a position as equal and a White proponent as not quite equal, then, call it what we want, neither one need be making a gross error. I agree that this kind of  variance (also relative to one'si own assessments) is normal. Critical reading is as important in chess as anywhere else.

@Topnotch, that is a good reply and very civilised. In the other thread on whether the forum is dying, perhaps this thread is an example of why ChessPubbers are not posting. They get shot down very quickly. there is no engagement, just a standard "biased" "prejudiced" response from a platform.
Now, I better run before I get shot down as well.

all of this time running statistics could have been used studying the open Sicilian!

Instead of judging bias by the outcome of the chosen games, I'd rather judge it by the quality of the analysis.

Also, asking authors to not be sympathetic towards the lines they play is a bit unfair, IMO. It is the fact that authors play and believe in these openings that makes their opinions worthwhile in the first place. E.g. Michalevski's Open Spanish coverage and Scherbakov's Triangle coverage.

Although I fully understand if you'd like more black ideas to be presented if you play the Sicilian as black. But this could be done by asking for it, rather than an accusation of bias.

With this said, I'm a subscriber, but don't play the Sicilian with either colour, so I'm not really qualified to comment on Sam's coverage. I generally skip through the Anti-Sicilian updates superficially.

an ordinary chessplayer wrote on 06/22/17 at 20:33:57:

I didn't take offence. You made a valid point, and I was just wondering what "evenly matched" might mean in terms of ELO difference.

I have to agree that MegaBase's "top games" statistics after 1.e4 c5 2.Nc3 is a bit misleading. One point is that, after 2.Nc3, White quite often plays Nf3 and d4 anyway, which normally leads to an Open Sicilian after ...cxd4 Nxd4. But that alone shouldn't explain a white score below 50%. The main reason presumably has to do with the difference in playing strength – perhaps 2.Nc3 is essayed more often than not by weaker players against stronger ones … 

To get a clue how well the Anti-Sicilians with 2.Nc3 do if the players are "evenly matched", I did the following analysis.

First, I looked at the games annotated by Sam Collins in the Anti-Sicilans section. Of those, 18 games began with 1.e4 c5 2.Nc3; they are classified under the ECO codes B23, B25 and B30. (As noted above, White scored 83.3% in these games ...) 

Then I did a search in MegaBase 2017 with the following parameters:

Position: after 1.e4 c5 2.Nc3
ECO: B23
ELO: both White and Black 2400 – 2500 ("evenly matched", so to speak ...)

The result: 732 games; White scored 55.1%.

I repeated this procedure for three more ELO intervals. The combined results for B23:

B23      
ELO interval      number of games      White's score [%]
2400 – 2500      732                          55.1
2500 – 2600      308                          51.3
2600 – 2700      70                            57.9
2700 – 3000      20                            47.5
total                  1130                        54.1

Obviously with this method one does not find games where, say, White was rated 2590 and Black 2610. But my ChessBase 13 does not appear to provide any easy ways of searching for games where the ratings of the white and black players differ by not more than a specified amount. At least I haven't found any ...

However, I think the numbers above give us a first valid estimate.

The analogous results for B25 and B30:

B25            
ELO interval      number of games      White's score [%]
2400 – 2500      292                          52.1
2500 – 2600      95                            48.9
2600 – 2700      28                            51.8
2700 – 3000      8                              68.8
total                  423                          51.7

B30            
ELO interval      number of games      White's score [%]
2400 – 2500      128                          57.4
2500 – 2600      50                            57.0
2600 – 2700      21                            73.8
2700 – 3000      4                              75.0
total                  203                          59.3

If we combine the results for all three ECO codes (1756 games played by – more or less – evenly matched players), we get an average white score of 54.1%, which must be close to what White should expect to achieve in most "regular" openings. 

By the way, Megabase 2017 tells me that, after 1.e4 c5 2.Nc3, in the "top games" White scores 47.3% after 2…Nc6. Go, figure …

an ordinary chessplayer wrote on 06/22/17 at 14:33:46:

What is, in your opinion, the biggest difference in playing strength (or ELO, for that matter) that would be acceptable for the players to be called "evenly matched"?

What is the lowest rating for such an analysis? Should games be included where both players are rated around, say, 1200? 1300? 1400? ... ?