 In this particular case it is fairly uncontroversial that avoidance of type II error should be given priority over avoidance of type I error. In other words, it is better to delay the flight and then find out that the engine was in good shape than to fly with an engine that turns out to malfunction. However, in other cases the balance between the two error types is more controversial. Controversies are common, for instance, over what degree of evidence should be required for actions against possible negative effects of chemical substances on human health and the environment.