[clinic · EX-02] Find the N where the ceiling stops moving

[akash-coded]

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Exercise: EX-02 — Find the N where the ceiling stops moving · difficulty 🟡

What this exercise asks

Read the exercise first; this thread is for when you are stuck, not instead of it.

Three ways people get stuck on this one

1. Reading the ceiling off Recall@N and stopping. Recall@N keeps creeping up long after full_chain_recall has stopped moving — see #28.

2. Sweeping N without holding k fixed. Two moving parts, one curve, no conclusion.

3. Calling the knee where the curve looks flat. Flat-looking and inside-the-noise-band are different claims; use paired_bootstrap between adjacent N values.

How to ask here

Post the numbers you got, the config that produced them, and what you already tried.
A question with a measurement in it gets answered in one round trip; a question without one
takes three.

If you have finished it, post the write-up in Show and Tell with the
[solution · EX-02] prefix rather than here — this thread stays for people who are stuck.