"they" say that parents want to know

how their child is performing comparative to the other children in the class. Can you imagine the same concern with health?
Yes but Doctor I want to know if Jimmy is healthier than Susie.
Well as a matter of fact, no he's not. He's 10% sicker than Susie and a staggering 50% sicker than Tommy. He is really sick. He is below average. He's in the 30th percentile for breathing and in the 20 th percentile for red cell blood count. He is average height and weight for age. He could do a lot better.
Oh, I see. Well thank you Doctor.