The major difference between traditional A/B testing and Volument is that the comparisons are based on _cohort analysis_. It takes two groups of visitors and places them side-by-side starting from the very first visit: how they gradually build awareness and interest (metrics from the first visit) before taking action (on the first visit or on later visits). Then you take a cutoff day (say Day 7) and compare what has happened (how much retention, conversions, sales, virality) before that day. The whole "traction" so to speak.