FWIW, my guess was at the 98th percentile, relatively close to the data (on the other hand, I was really bad at guessing the position of the ball in yesterday's football/soccer test).
The median guess probably suffers from a "connect the dots" bias, going from (0,0) to (100,100) through the suggested point.
Seeing how smooth the data is, it results from a large sample, and the measurements are objective, I fail to see how they could have gotten them wrong.
He's saying that, "Just because you can't guess the trend in the data (eg. the track of a soccer ball in yesterday's match) doesn't mean that something is wrong with the data; you often need to double-check both your hypothesis and your data. And in this case your hypothesis was probably at fault due to inherent bias rather than inaccuracies in the data."
The median guess probably suffers from a "connect the dots" bias, going from (0,0) to (100,100) through the suggested point.
Seeing how smooth the data is, it results from a large sample, and the measurements are objective, I fail to see how they could have gotten them wrong.