OK, so they've analyzed 4.9 million moves. How many double blunders did they find in the set? If the hypothesis of independent events is true there should be ab

OK, so they've analyzed 4.9 million moves. How many double blunders did they find in the set? If the hypothesis of independent events is true there should be about (4.9e6 / 10,000) = 490 doubles in the data set. An obvious way to test accuracy of the model is to compare that to the actual number. Why hasn't that comparison been done/mentioned?