1 00:00:00,000 --> 00:00:03,000 Y will always be less extreme. 2 00:00:03,000 --> 00:00:08,000 The key to understanding this simply is this equation. 3 00:00:08,000 --> 00:00:18,000 This is what tells us that the standard scores have a regression coefficient â¤ 1. 4 00:00:18,000 --> 00:00:25,000 We said it's 1, and so because it's not 1 it must be less than that. 5 00:00:25,000 --> 00:00:28,000 That means the standard score shrinks. 6 00:00:28,000 --> 00:00:35,000 If the standard score shrinks that means if it's negative it moves this way. 7 00:00:35,000 --> 00:00:37,000 If it's positive it moves this way. 8 00:00:37,000 --> 00:00:40,000 That means there is more area under here, 9 00:00:40,000 --> 00:00:45,000 so this has to be a little more area than this. 10 00:00:45,000 --> 00:00:49,000 Therefore, y will always be less extreme. 11 00:00:49,000 --> 00:00:51,000 This is the concept of regression. 12 00:00:51,000 --> 00:00:55,000 That is regression to the mean. 13 00:00:55,000 --> 00:00:58,000 If someone is exceptional in one thing, 14 00:00:58,000 --> 00:01:02,000 we will always predict that person to be a bit less exceptional 15 00:01:02,000 --> 00:01:07,000 in that other thing if there is any error.