A noninferiority trial is a type of randomized trial that aims to establish if treatmenet X effectiveness is not substantially less than the existing standard. Unlike superiority trials that are designed to show that one treatment is better than another, a non-inferiority trial is designed to show that a new treatment is ‘not unacceptably worse’ than the current standard therapy. You want to see if the drug you are testing is good enough compared to the standard.

Say you wanted tacos from your favorite place across town cause they have the best tacos but there is another taco place that is across the street the tacos are not as good but they are pretty close and it is a 20 second walk not a 20 minute drive. You might quickly in your mind calculate the trade off and say well the place across the street is noninferior.