chess.com Analysis "Accuracy" - What score is computer like for a given rating? I have a few questions about engine use detection at online games on chess.com:


Let's say both players are rated 1800 on chess.com online play and
they make n number of moves in a game.

White has 90% accuracy due to very decent moves, while black has an accuracy of 97.5%. 


  If n &gt; 20 (less likely to be good moves by fluke), does this
  accuracy score mean that black cheated?


From my understanding the accuracy also depends on the number of moves made. For example, if you only made 3 moves and followed a well known opening your score will be 100% and that is not suspicious. 


  Thus, at what n does the accuracy start to matter when it comes to
  detecting a cheat?

Chess.com seems to not act upon reports of cheating players.


  Does this mean that those players did not cheat?
  
  How to escalate the situation to avoid losing those valuable games?


For example, some players cheat in crucial games in tournaments where a win allows them to advance over you.

  What stops someone from turning on a chess engine, when they
  have a losing position, until they gain an advantage (at which point
  they play without the engine)?


This seems like it would be impossible to detect as there will be
typical moves (normal moves they make) from their previous games, with a few amazing moves sprinkled in.
I'm a 1400-1500 rated blitz player on chess.com. Looking through my archives, I see that just this month I had a 34 move game, at a 3 2 time control, where I was rated at a 97.4% accuracy. And I know I wasn't cheating.

When I look at my recent daily games (where I'm rated higher, around 1900) I see a 46 move game where I was rated at 99%.

You can't tell anything from a single game.