Claims often suggest large effects. But in management large effects are rare.
Large effects (an effect that anybody can easily see because it is substantial) are easy to detect, but few management interventions have effects that are so large that reliable measurement methods or a fair comparison are not needed.
Therefore, in management, claims of large effects – especially when they are not based on evidence that involves a fair comparison of interventions – are not trustworthy. Expect management interventions to have moderate to small effects, rather than dramatic effects.
Claims of large effects are likely to be wrong