A statistical term used as a benchmark in clinical trials. The significance level of a difference is used to describe approximately how likely it is that the result of a comparison was obtained "by chance". The importance of the p-value is often overestimated in interpretations of a result, because the p-value does not indicate the size of the difference in a comparison of, for example, two drugs, but whether the observed difference, whether large or small, could be random or real. Statistically significant does not mean eo ipso clinically relevant.