Orton's Arm

Thank you for making your position on point #2 perfectly clear.

You seem to be saying two different things here: 1) measurement error is not required to produce variation in individual scores, because a given person's ability to think varies based on the amount of rest, time of day, and other factors. 2) someone who scores a 180 on an I.Q. test (even one with measurement error) will, on average, score a 180 upon retaking the test. I agree with point #1, and strongly disagree with point #2.

You're wrong, but let's continue this over on the "regression toward the mean" thread.

You're wrong, as I've shown here

Both the metaphors you've used (anti-biotics and painting into a corner) have no relevance to Reagan's policies.

The reason I'm still arguing is because people like you a) don't understand what I've been trying to say, and b) think they do understand it.

Wrong, again. Suppose you had a population with 10 190s, 100 180s, and 1000 170s. Measure the I.Q.s of these people with a perfect test. The 190s will all get a 190, the 180s will all get a 180, etc. But now suppose it's possible to get lucky or unlucky on the test due to an element of measurement error. Someone who scores a 180 could be either a lucky 170, a luck-neutral 180, or an unlucky 190. Of those three possibilities, the lucky 170 is more likely than the unlucky 190. This is because there are more 170s available for getting lucky, than there are 190s available for getting unlucky. Therefore, someone who scores a 180 on the test the first time around is expected to get a somewhat lower score upon retaking the test. This phenomenon is what I've been describing all along. It requires measurement error to happen, just as it requires a non-uniform distribution to happen. To say that either of these phenomenon alone "cause" the phenomenon would be mistaken; as both are required for it to take place.

I've been saying the exact same thing all along. Maybe some of it's finally starting to penetrate those 16 inches of bone that separate your "brain" from the outside world.

Is the thingy there because you stole that exact pile of, um, of text from Bungee Jumper? The next time you steal something, make sure it's worth stealing!

No, I've been saying the same thing all along. But now you're finally starting to understand it.

Are you trying to blame Reagan for September 11 or the war on terror? Reagan played an instrumental role in solving the problems of the Cold War. He didn't create the problems we have today.

The only point I've been trying to make here is that someone who obtains an exceptionally high score on an I.Q. test will likely obtain a slightly lower score upon retaking the test. That 150 score is more likely to signal someone with an I.Q. of 140 who got lucky, than someone with an I.Q. of 160 who got unlucky.

Truman is to the Cold War what Clinton is to welfare reform. Yes, they both did something, but not because they wanted to. Reagan based nearly his whole presidency around winning the Cold War--a goal which he achieved. 1. He built up the U.S economy. 2. He used this increased economic strength to build up the U.S. military 3. Instead of blathering on about common ground between America and the Soviets (as Carter did), Reagan clearly defined the Soviet Union as an Evil Empire. He contrasted this evil with the vision of freedom he articulated for America. Reagan's view was expressed with such simplicity, such clarity, and so much repetition, that it was able to spread far beyond American borders, and influence events in far away places. 4. Reagan supplied weapons to Afghan rebels--rebels which were ultimately successful in ending the Soviet occupation of their nation. I've heard it said that the Afghan War was the Soviets' equivalent of Vietnam. 5. Reagan restored American prestige in the world. He walked a fine line, and avoided Carter-like weakness, as well as George W. Bush-like overaggression and overbearing behavior. 6. He helped reduce the number of nuclear weapons in the world. First he built up the U.S. nuclear weapons supply, then he traded away those buildups for Soviet concessions. Ultimately, Reagan's vision of freedom was delivered so persuasively that Gorbachev felt he had to do something. So Gorbachev began offering limited freedoms to the Soviet people. This paved the way to the collapse of the Soviet Union. Democrats fought Reagan every step of the way. They fought him when he wanted to increase military spending; saying the money should be used for schools. (Never mind the fact that a voucher system would increase school effectiveness while reducing cost.) Democrats successfully resisted Reagan's efforts to send military aid to the anti-communist freedom fighters in Nicaragua. Democrats called Reagan a war-monger and a cowboy after his "Evil Empire" speech. They accused him of taking too hard a line against the Soviet Union, and repeatedly urged him to soften his stance. Democrats resisted nearly every step Reagan took to end the Cold War.

I'm not sure why you felt the need to go through all that. All Wraith was saying is that a person's I.Q. scores ought to vary from one test to the next, because that person's underlying ability to think varies based on amount of rest, the time of day, etc. That particular post wasn't intended to address the heart of what we've been arguing about here.

If you dig through the "Err America Files Chapter 11 Bankruptcy" thread, you'll see that I've said that both measurement error and a non-uniform distribution of I.Q.s are necessary to create the phenomenon I've been describing. Here's a quote from page 12 of that thread: Bungee Jumper responded with this: Ramius responded with this: All along, I've been saying that people who get very high scores on I.Q. tests tend to do a little well upon being retested. If you look at the first four posts on page 16 of the Err thread, you'll see Bungee Jumper ridicule this view.

Measurement error is a necessary component in the phenomenon I've been describing. If you had an error-free I.Q. test, and 100 people who scored a 140 the first time they took the test, that group's expected average score on the retake would be 140. But if the test involves measurement error, someone who scored a 140 on the test could be a lucky 130 or an unlucky 150. A group of 100 people who scored a 140 on this error-possible test will, upon retaking it, obtain a lower average score the second time around. (Some people will obtain higher scores the second time around, but there will be far more people who obtain lower scores.)

Once again, you're trying to throw him into this debate. If Wraith wants to dispute what I've been saying, let him do it. Don't put words into his mouth.

Whether intentionally or otherwise, you are throwing Wraith into this discussion by implying he's expressed disagreement with the phenomenon I've been describing.

Instead of calling it luck, you're welcome to call it measurement error if that makes you happy. Assuming people's results on a given test are due at least in part to measurement error, those who obtain extreme scores on the test will tend to score closer to the population mean upon being retested. Do you dispute that?

I understood the example perfectly. I think Wraith was trying to provide a better understanding of the technical definition of the term "regression toward the mean." However, I've said all along that those who obtain extreme scores on a partially luck-based test tend to score somewhat closer to the population mean upon being retested. Wraith was not disputing this. Are you?

No, I don't feel I'm the only one who's right. The people who wrote the articles to which I linked obviously understand the phenomenon a lot better than you do.

A good example, and I agree--repeated measurement causes regression toward the true mean.

I've never contended otherwise. I've consistently said that if you select a group of people with very high I.Q. scores, that group will tend to have been luckier than average on the I.Q. test. When you retest that particular group, individual members will once again get lucky or unlucky on the test. But in the aggregate, the positive luck the group experienced the first time around is expected to become neutral luck the second time. This causes the group's average to be somewhat closer to the population mean on the retest. Of course the net effect is zero. That's not in question here. My point is that if you have a group of people who scored a 150 on an I.Q. test, and if that group sits down to retake the test, the expected average score for that group's retest is less than 150. At the individual level, this means that if someone who scored a 150 on an I.Q. test is sitting down to retake it, his most likely score is less than 150. This is because that 150 score is more likely to signal a lucky 140 than an unlucky 160. In the I.Q. test example, measurement error is necessary for the behavior I've described to take place. Those who get very high scores the first time they take the test tend to do a little less well upon being retested. (Obviously this is an aggregate phenomenon, as some of those being retested will do the same or better the second time around.)

Here's another quote: