Confidence Level Definition The probability that the winning variation of your A/B test had more conversions for reasons other than chance. Before declaring a winner, you want a confidence level of 95% or more, as well as a sufficient number of conversions. Conversion expert Michael Aagaard explains why confidence level is a necessary, but not sufficient factor in determining a valid test. “Running an A/B test without thinking of statistical confidence is worse than not running a test at all.” — @peeplaja Tweet This Resources The Ultimate Guide to A/B Testing See How Dynamic Text on a Landing Page Helped Increase Conversions by 31.4% [A/B Test Reveal] A/B Testing Significance Calculator How to Build a Strong A/B Testing Plan That Gets Results