> Accounting for squaring the distance You actually don't want to square the distance, since you are not trying to compute the acceleration due to gravity, you

> Accounting for squaring the distance You actually don't want to square the distance, since you are not trying to compute the acceleration due to gravity, you are trying to compute the gravitational potential (since that's what affects clock rates), which goes like 1/r, not 1/r^2. So the Earth's effect should be about 10^14 larger than the effect of the people in the stadium. (Which is still several orders of magnitude larger than the sensitivity of the clocks, so it's entirely plausible that the clocks were detectably affected.)