Design better experiments

An experiment should make the next decision easier. Start with a question you can answer, rather than a redesign you hope will work.

Write a specific hypothesis

Use this structure: “For this audience, changing this element should improve this outcome because of this observed problem.” Ground the problem in evidence such as customer feedback, usability observations, or a measured drop-off.

Choose the decision rules before launch

Define the primary metric, guardrail metrics, eligible audience, and duration. Estimate the sample you need using your baseline and the smallest improvement worth acting on. If traffic is too low for a useful controlled test, use qualitative research or a carefully described before-and-after evaluation, acknowledging its limitations.

Keep the comparison interpretable

Change one coherent idea at a time. Check that assignment and event collection work, and avoid changing unrelated campaigns during the test where possible. Do not end a test just because an early result looks encouraging.

Record what you learned

A result without a lift can still rule out an assumption. Record the hypothesis, change, sample, uncertainty, outcome, and next action. Keep the decision separate from the story you wanted to tell.

Your next step

Write one experiment brief. If you cannot explain why the change should help a particular customer, return to the research before building it.