Performance rating of a list of games

 From version 2.20, a new tab named Performance Rating has been added to the database game editor. 

The Performance Rating tab in the Lucas Chess database editor lets you calculate players’ Elo performance over a set of games. You can select several games (for example, from a tournament or a training session) and see what level of play the results represent. In practice, you open your game database (Tools → Databases), select the desired games, and go to the Performance Rating tab. The program then calculates, for each player or colour involved, the performance Elo they would need to have scored the result they did.

As explained on Wikipedia, a player’s performance rating is the Elo rating a player would have if their results produced no net rating change. In simple terms: it shows the level you played as if you had that rating.

It measures how well someone played compared to their opponents’ ratings. For instance, if you have a 1700 Elo rating and you score more than 50% against players rated 1700, your performance is above 1700. On the other hand, if you draw 50% against opponents rated 2000, your performance is around 2000.

Performance does not mean that you found particularly good moves, tactics, or plans, or that they were bad. Performance is based solely on results.

When evaluating performance, only points (Win, Draw,Loss) and your opponents Elo Rating are taken into account, not moves nor your rating. 

Several methods simplify this process by using just these two values.

Available Methods for Calculating Performance

Lucas Chess offers three popular methods to calculate performance:

1. FIDE Method – the official method by FIDE. Performance = Opponent Average Rating + d, where d depends on score percentage.
2. Mathematical (Exact) Method – solves for the rating that would yield the actual score against those opponents.
3. Linear Method – a simplified formula: Performance = Opponent Average + (800 × Score%) – 400.

Each method has its own use cases, with Linear and FIDE being simpler, and Mathematical being the most accurate.

From the Config option, you can change the method used.

How to Select Games and What’s Required

To use this feature:
1. Load a game database in Lucas Chess.
2. Select the games you want to include, all are considered if none is included.
3. Go to the Performance Rating tab.

Note: Each game must include both players’ Elo ratings and a result. Games missing this information won't be included in the calculation.

Displayed Columns and Their Meaning

In the Performance Rating tab, you’ll see several columns:

1. Players – Listed alphabetically by default

2. Avg Elo – Average Elo of the player in the selected games

3. Performance – Rating calculated using the selected method

4. Performance White – Performance in games played with White

5. Performance Black – Performance in games played with Black

6. % Score – Three values separated by dashes: total score, score with White, and score with Black

7. Score – Same structure as % Score, but in absolute points (Win = 1, Draw = 0.5, Loss = 0)

8. Results – Three blocks (overall, White, and Black), each showing the number of wins, draws, and losses (e.g., 3/2/5)

9. Avg Opponent – Average Elo of opponents, broken down by all, White, and Black games

Sorting the Data

You can sort the data by clicking on any column header. This helps quickly identify who performed best or played the strongest opposition.

Recommended

Make sure that games match the same event, site, time control as to get useful results.

Mixing rapid games in Lichess Arena with blitz games on Chess.com is not advisable because the Elo ratings are different.

Use between 5 and 50 games as Performance rating approaches Elo rating with the number of games.

With less than 5 games the evaluation system hurts the limits of being correct as it is only a conceptual model and no science. With more than 50 games your statistical wins will likely equal the losses and thus the Performance corresponds mostly to your rating.

Large Databases: for fast processing, use the filter functions or make a selection of games.

Further Reading

For more details, see the article on Performance Rating in chess on Wikipedia: https://en.wikipedia.org/wiki/Performance_rating_(chess)

Promoted by Stefan Akall 

Created based on suggestions and feedback from Stefan Akall. 

And the Eric betatest as usual.