Peeking at Experiment Results Early Is a Habit, Not a Mistake, Break It

Ask any marketer running A/B tests whether peeking at results early inflates the false positive rate, and nearly all of them will say yes correctly. Then watch them check the dashboard on day three of a planned fourteen-day test anyway. The knowledge isn't the problem. The habit of checking is, and no amount of statistics education fixes a habit.

Why the knowledge doesn't change the behavior

Checking a dashboard is free, immediate, and satisfies real curiosity in the moment — all the ingredients of a hard-to-break habit. The cost of peeking (an inflated false positive rate) is abstract, deferred, and only shows up weeks later when a 'win' fails to replicate. That's a terrible trade for behavior change even when everyone involved understands the math perfectly.

You don't fix a habit with a statistics lesson. You fix it by removing the thing that makes the habit easy.

What actually worked for the teams I've seen fix this

• Lock the results dashboard behind a date, not a permission — nobody can see the number until the pre-committed duration ends, full stop.
• Use sequential testing methods designed to allow early stopping without inflating false positives, if the business genuinely needs the option to call tests early.
• Make the pre-registered sample size and end date visible to stakeholders before the test launches, so there's a public commitment to point back to when someone asks for an early read.
• Separate the person running the test from the person who wants the answer — a PM asking for a peek is harder to resist than a dashboard that simply isn't available yet.

I stopped trying to convince teams that peeking was statistically risky, because that argument had already been won and lost zero behavior. What worked was removing the dashboard access until the test was actually done. Make the easy thing the right thing, and the habit takes care of itself.