Answer
Hi, to be clear about this statement,
A criterion by which something is being compared is a standard for evaluating something.
Step-by-step explanation
Well, we that we cannot make a comparison between two or more things without having criteria. There should exist a point of reference for us to make a conclusion about a process, activity or quality attained by something or a person. For example, we can say “Christiano Ronaldo is the best football player in the world” , where standard could be a combination of traits and data such as penalty goals scored, championship won or his current net pay. From one of these standards, an evaluation can be made compared to other football players.
Hope this helps!