Glossary · Testing · also analysis plan, pre-registered analysis plan
What is pre-registration?
Pre-registration is writing down a test’s plan before it starts: the primary metric, the minimum detectable effect, the significance level, the guardrails and the stopping rule. Stored with the test and fixed once traffic flows, it stops the analysis being chosen after the data are seen, which is how a team finds a win in a metric or segment nobody planned to read.
- Reviewed 6 October 2026
In more detail
Without a plan written in advance, every test has many ways to win: a different metric, a segment, a shorter window, a different stopping day. Pick the best of those after the data arrive and you will find a win in noise. Pre-registration closes those doors by deciding them first.
It also makes a result reviewable. Anyone reading the outcome can check it against what was promised: the metric that was meant to move, by how much, at what significance level, and which guardrails had to hold.
A pre-registration can still be changed, but only openly, with the change and its reason recorded. A change made after the data have been seen weakens the claim.
Key points
- Metric, minimum detectable effect, significance level, guardrails and stopping rule, written first.
- Prevents choosing the analysis after seeing the data.
- Makes a result checkable against what was promised.
How Liftable relates
Related terms
Guides that go deeper
- Testing · 5 minHow to split-test when you don’t have the trafficMost stores can’t read a purchase-level A/B test in a sensible time. Why, and the adjustments that make testing work at the volumes stores actually have.Read
- Testing · 7 minHow to test a fix without breaking your live storeTest through a route that never edits your theme’s code, read the change first, run one test per surface, keep the rollback to one switch. The safe sequence.Read
Last reviewed against the product on 6 October 2026.
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