Randomised trial
Also called RCT, Randomised controlled trial
A test where chance decides who or what gets the treatment, so the two groups differ only by luck and by the thing you are testing. That is what lets you say one thing caused another, and not just that they went together.
If you choose which tasks to give the agent, you will pick the ones you expect it to help with, and comparing times afterwards mostly measures your choice. It is why a before-and-after on your own work proves so little, and why a coin flip on your next ten tasks proves more.
“I want to know if using you on this kind of task is worth it. Make a table for my next 20 tasks. I write each task down first, then assign it with python3 -c "import random; print(random.choice(['agent', 'hand']))". Record minutes and whether it merged without rework. I don't get to swap after the flip.”