How we test
MedCards compares options to improve the product. Each comparison has an ethics class.
ET0 Operational
Staged rollouts, fixes and performance changes. The terms of use and the privacy notice apply.
ET1 Product comparison
Two acceptable options that do not change how you study: copy, onboarding order, layout. You never pay more than the list price because of a group.
ET2 Learning-affecting comparison
Two options inside the evidence-based range, for example 2 or 4 buttons, or a desired retention of 0.85 or 0.90. The app shows "Settings under evaluation" and you can leave the test in Settings.
Guardrails
Guardrail metrics stop a test that worsens retention, crashes or cancellations. A control group stays out of tests for the semester. Tests that hide the Free plan, manipulate mood or send reminders in quiet hours are not allowed.