Saturday, June 20, 2026 · 9:41 AM
ok dumb question, what’s the deal with the metric is not the user?
Goodhart's Law and Campbell's Law show how metrics drift away from reality. When teams chase the number hard enough, the signal stops representing the user and starts rewarding whatever moves the dashboard.
so the villain is... my brain trying to be helpful?
pretty much
your brain hates blank space, so it fills it with the nearest sample: you
The economist Charles Goodhart identified this in 1975 while studying monetary policy.
that feels rude but accurate
it’s like driving with only the speedometer. useful, until you forget there are people in the crosswalk
wait so the fix is just ‘ask users’?
annoyingly, no
asking helps, but the chapter is warning you about the gap between what feels true and what survives contact
TL;DR: Goodhart's Law and Campbell's Law show how metrics drift away from reality. When teams chase the number hard enough, the signal stops representing the user…
ok that’s the part people skip
yep. the number stops showing the user is the trap door
then it shows up as facebook found this too
In 2018, Facebook’s internal research team built a presentation warning that the News Feed algorithm was exploiting what they called the human brain’s attraction to…
so what do i actually do differently on monday
pair every metric with the user behavior it’s supposed to protect
if the number rises while the experience gets worse, believe the experience
and if a choice only works for informed, patient, caffeinated people, treat that as a bug
that’s the series tbh
design psychology is mostly noticing the human nonsense before it ships
ok send me the next one after i recover
Read Sat, Jun 20 · 10:03 AM