the bell curve is one giant "type II" error

Jake Shannon (
10 Dec 98 19:41:01 PST

"A null hypothesis is always one of status quo or no difference... A Type II
error occurs if the null hypothesis Ho is not rejected when in fact it is false and should be rejected."

                    (David Levine, 1998)

Hi, my name is Jake. I am a long time lurker and this is my first post to the extropians list. I too have read the Bell Curve but find it somewhat unpalatable. I consider myself an individualist and libertarian and thus found much trouble with surveying errors in the book. It is essential to examine the purpose of the survey, why it was conducted, and for whom. Technically speaking, there are four types of survey error (Groves, R. M., Survey Errors and Survey Costs, New York: Wiley, 1989): 1. coverage error- results from the exclusion of certain groups of subjects from this population listing so that they have no chance of being selected in the sample.
2. nonresponse error- results from the failure to collect data on all subjects in the sample.
3. sampling error- reflects the heterogeneity or "chance differences" from sample to sample based on the probability of subjects being selected in the particular samples.
4. measurement error- refers to inaccuracies in the recorded responses that occur because of a weakness in question wording, an interviewer's effect on the respondent, or the efoort made by the respondent. Murray and Hernnstein commit the first, third, and fourth errors IMHO. The fact that they get a normal distribution when they sample a large group of subjects should be no surprise to anyone familiar with undergraduate statistics. The problem is one of GIGO (garbage in, garbage out). I met Murray once while he was speaking in front of a decent sized libertarian audience at Laissez Faire Books and he caught a lot of flack there and I doubt there was anyone there who would consider themselves a "leftist". I wrote a short non-technical piece and posted it to the web at the very bottom of Please read it critically (keep in mind I wrote it journalistically) and get back to me if you don't agree with my conclusions... With Liberty and Justice,

"Democracy is the recurrent suspicion that more than half
of the people are right more than half the time."

                            -E.B. White

"Democracy is the recurrent suspicion that more than half
of the people are right more than half the time."

                            -E.B. White
I read the entirety of The Bell Curve, and checked over some of the statistics behind the models, so I think I can claim to understand it.

The book makes the following arguments:
1) There is a significant positive correlation between IQ and economic success.
2) There is a significant positive correlation between measured IQ and 'intelligence'.
3) A substantial part of IQ is hereditary. 4) To the extent that social and ethnic groups represent distinct gene pools, they can have differences in average measured IQ.

All of these propositions were based on hard data, which was subjected to exhaustive statistical analysis to filter out other correlations. The IQ effect remains fairly large even after correcting for education level, social status, age, and all sorts of other factors.

Of course, the authors were immediately denounced by the American Left, which decrees that all people are identical and the only possible explanation for any difference in outcomes is discrimination. Nevertheless, their work remains the closest thing to scientific proof that I have ever seen in the social sciences.

Billy Brown

Get free e-mail and a permanent address at