When studies find little or no difference between the comparison groups it is described as having “no evidence” of a difference. This is sometimes misinterpreted as meaning that there is definitive evidence of “no difference” between the groups, which is incorrect.
Just because a study cannot find evidence of a difference does not mean we are sure there is no difference. A lack of evidence simply means that we cannot be sure whether there is an important difference between the groups or not. Therefore, we cannot be sure whether one treatment is better or worse.
REMEMBER: Consider carefully whether the study is reporting that there is definitely “no difference” or that there is a “lack of evidence”.