Rationality Quotes April 2012

Oscar_Cunningham

Here's the new thread for posting quotes, with the usual rules:

Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself
Do not quote comments/posts on LW/OB
No more than 5 quotes per person per monthly thread, please.

Here's the new thread for posting quotes, with the usual rules:

Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself
Do not quote comments/posts on LW/OB
No more than 5 quotes per person per monthly thread, please.

If you know the scores of two different golfers on day 1, then you know more than if you know the score of only one golfer on day 1. You can't predict the direction in which regression to the mean will occur if your data set is a single point.

The following all have different answers:

I play a certain video game a lot. The last time I played it, my score was 39700. What's your best guess for my score the next time I play it?

(The answer is 39700; I'm probably not going to improve with practice, and you have no way to know if 39700 is unusually good or unusually bad.)

My friend and I both play a certain video game a lot. The last time I played it, my score was 39700. The last time my friend played it, his score was 32100. What's your best guess for my score the next time I play it?

(The answer is some number less than 39700; knowing that my friend got a lower score gives you a reason to believe that 39700 might be higher than normal.)

I played a video game for the first time yesterday. My score was 39700, and higher scores are better than lower ones. What's your best guess for my score the next time I play it?

(The answer is some number higher than 39700, because I'm no longer an absolute beginner.)

True, a single data point can't give you knowledge of regression effects. In the context of the original problem, Kahneman assumed that you had access to the average score of all the golfers on the first day.

I played a video game for the first time yesterday. My score was 39700, and higher scores are better than lower ones. What's your best guess for my score the next time I play it? (The answer is some number higher than 39700, because I'm no longer an absolute beginner.)

I'm not sure it's true that the answer is higher than 39700, in this case. It dep... (read more)