<b>Day 2 of the test and I peeked. Big mistake.</b>

<b>Day 2 of the test and I peeked. Big mistake.</b>

Variant B was crushing. +22%. I texted my partner 'we found it.'

Day 5: +3%. Day 8: dead even.

That early spike was noise. Small samples swing wild. If you call it on day 2 you're just gambling on randomness and calling it skill.

The fix that saved me: I now set a fixed sample size BEFORE the test starts. No reading results until I hit it. I literally hide the dashboard.

If you must peek for sanity, use a sequential test (always-valid p-values) so early looks don't inflate your false positives.

— Decide your sample size first
— Don't call a winner before you hit it

Go set a stop number on your running test. Then close the tab.