[stch]

Uh, how does the first graph not have a correlation? As a first order guess, that looks like a very strong correlation to me, probably at least .10 R^2 if you fit a regression to it. I'm guessing the author avoided fitting a regression to the original data because it actually is significant.

Not to mention, it's just plain incorrect statistics if you don't do weighted least squares regression (instead of OLS) on the averaged data set.