In any A/B, Multivariate, or Split test, the variation with the best conversion rate is called the winner.
VWO uses SmartStats to run tests and find the winning variation. SmartStats calculates with 99% probability a conversion rate range in which the true conversation rate of a variation lies. The more data it collects, the shorter the range of the highest likely values gets. When the difference between the lower limit of the winning variation is at least 1% higher than the upper limit of the losing variation, SmartStats declares it as the winner.
For example, if the conversion rate for Control lies in the 10–20% range and the conversion rate for variation 1 lies in the range 21.1–27.0%, variation 1 is declared a winner because even in the worst case scenario, it improves the conversion rate by 1%.