# Novelty Effect Consider the following graph, it shows the average game purchases per day between two groups, control and treatment, in an [[AB Testing|A/B Test]]. What is evident from the graph is that there seems to be an increase in purchases which subsequently diminishes as time goes by. ![[novelty_effect_abtesting.png]] This is a good example of novelty effect, which is that as you release new features, there will be an increase in activity just because it is new. The test needs to run long enough so that this effect is controlled for.