[Gunax]

But we would not expect the coin toss to have a correlation. Whereas we might expect a correlation between actual and perceived ability.

So yes, both are null results, but only one is interesting.

For instance, we would probably expect there to be a correlation between height and ability to dunk a basketball. If someone were to show that there is not a correlation, that would be an interesting result. Just because random data would match my result doesn't mean my result is nonsensical. Getting results that look like random data is still a result--it just means there isn't a correlation.