A randomized trial comparing the efficacy of two drugs showed a difference between the two with a p value of <0.005. In reality, however the two drugs do not differ. This therefore is an example of:

Ans is 'a' i.e. Type I error (alpha error) There are two types of error in statisticsType I (or alpha) errora statistical significant difference is found but this is in fact not true.It is only by chance that a statistical significant difference between groups is found, there is no difference actually.eg. as in the question the two drugs do not differ but the randomized trial shows a difference.Type II for beta) errorwhen a study fails to prove a statistical significant difference, when actually there in one.eg. Aspirin is not able to prevent MI. (this occurs because of small no. of samples)