Guided tour · Evidence · step 9 of 11
Zero observed failures is not a rate of zero
The most persuasive number on a leaderboard is often the one with the least evidence behind it.
First, commit to an answer
A decoder reports 0 logical failures in 10,000 shots. What is its logical error rate?
Decide before you follow the link. Nothing is recorded — the value is in having been wrong on purpose once.
Now go and look
Find a run with no observed failures and read what the rate column says and does not say.
What you should see
Unknown, but below roughly 3.8×10⁻⁴ at 95% confidence. It is not zero, and a zero-failure row would otherwise sort to the top of every ranking.