The difference in rating changes between same rated people

in the starters 141 div 2 contest this person who was rated 1704 before the contest and I was rated 1705 after the contest ends i got 392 rank and got my rating increased by 30 (1735) ,and other person who had 1704 rating who got rank 595 got rating increased by 38(1742) .Why there is difference ? why the person with more than 200 rank of mine got increased 38 with almost same rating before the contest?


The difference in rating changes can be puzzling, but it boils down to how the Elo-based rating system works on CodeChef. This system predicts how well you should perform based on your initial rating. If you exceed these expectations, you get a bigger boost. In this case, the other person, who had a rating of 1704, might have faced tougher opponents or performed better relative to their expected performance. This could explain why their rating increased by 38 despite having a lower rank than you.

The system also considers the difficulty of the contest and how others with similar ratings performed. So even if your rank was higher, the other person’s performance, given their opponents and expected outcome, might have been more impressive, leading to a higher rating gain. It’s a complex mix of your rank, the ratings of those you competed against, and how well you did compared to what the system expected.

Ratings adjust based on how you perform relative to the system’s expectations. If they were expected to rank very low and ended up ranking 595, this is a significant overperformance, hence a larger rating gain.

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