11 yr old doing Graduate level statistics...WTF?

Your child's abilities are above and beyond the average 11 year old. He probably has a very high IQ overall and scores extremely high in Mathematical/Logical/Spatial Abilities. I believe that each person has a portion of intellectual abilities that are stronger than others. I am great with Language/Vocabulary/ogies, but I take what seems like a long time to understand math, and yet I have a slightly higher than normal IQ. So, no, I do not believe you're stupid. I think you just have other aspects of your intelligence that are stronger.