>In particular, the mean moves-per-game that he displayed it is simply the actual mean of the data set. It's not an estimate of that mean, if I'm understanding

>In particular, the mean moves-per-game that he displayed it is simply the actual mean of the data set. It's not an estimate of that mean, if I'm understanding the article correctly. So what does it mean to display a confidence interval for a parameter that's known rather than been estimated? Technically, I don't have the "true" mean because this data set isn't a set of all games ever. As such, I'm treating the games I have as a sample of all games ever, and providing an estimate of how confident I am in the mean I'm reporting. >I notice that the confidence interval is shrinking around his mean -- is that because there are more recorded games Exactly! Law of large numbers.