For that matter, how do we apply the "Outside View" advice? Based on the LessWrong survey results, "look at the general population of age X" is a lousy way to predict an average lesswrongian's personality at age X; presumably that's true for age X+10 too. "If you match the average of lesswrongians at age X, look for their average at age X+10" might be decent advice under the cynical view that "having had 10 extra years to read LessWrong won't lead to significant personality changes", if the data wasn't too sparse.