Was the study big enough? Two "café" rules

When reading an article, we often wonder whether the study was large enough. If a study does not find a statistically significant effect (e.g., at P < 0.05), it may be because the study was too small or because there actually is no true effect. You should check whether the CIs show that the data are consistent with a clinically important effect, even though the effect was not “statistically significant.”