[clinic · EX-20] Build a third bias probe

[akash-coded]

Exercise clinic. One long-running thread per exercise. Ask here rather than opening a
new thread — the answers accumulate where the next person will look for them.

Exercise: EX-20 — Build a third bias probe · 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. A probe that measures a property the judge is supposed to reward. Longer answers being scored higher is only bias if length is not actually better here.

2. Not holding content constant. If the probe changes what is said as well as how, it measures nothing.

3. Reporting the bias without asking whether it is consistent. A consistent bias cancels in a paired comparison; an erratic one does not.

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-20] prefix rather than here — this thread stays for people who are stuck.