IQ by Gender, Mean and Standard Deviation; Male Female Pay Gap

From: A
Sent: Monday, January 29, 2018 10:07 AM
To: Walter Block
Subject: Hello Dear Man.

We met at a convention some years ago. I recently heard you interviewed on an old Lew Rockwell podcast, and you were talking about psychometrics, a subject of which I am fond. The show was partly about the “Liberal” responses to some comments you made at the Baltimore campus of Loyola, about the discrepancy between men’s and women’s wages, and those between Blacks and Whites. You told Lew that women have the same average IQ as men. And that their distribution curve is tighter than men’s. I didn’t know this. I heard about the tighter cluster of Chinese people; but Richard Lynn denies this. So I’m writing to ask if you know any more interesting facts about IQ; and to ask where you got this info. Thank you so very much Walter. Peace.

Dear A: Here is a bibliography on information of this sort, below. I also attach a second edition of that speech I gave at Loyola University Baltimore on the pay gap and male and female IQs.

Again, my thanks to my friend Tom DiLorenzo, who invited me to speak at his university on this topic.

March 25, 2009. New Orleans, LA. Loyola University New Orleans, Economics Club. “Is the capitalist system guilty of racism, sexism? No.: Walter E. Block responds to his politically correct critics, defending against charges of racism and sexism. Pay gap. Glass Ceiling.;;;;;;;; q&a too;;

Block, Walter E. 2008. “The Idea Police vs. Walter E. Block : A (Not So) Funny Thing Happened To Me in Baltimore.” November 18;;;

Block, Walter E. 2008. “Afraid to debate.” December 3;

Block, Walter E. 2008. “More Controversy Over Female-Male Pay Gap.” December 5;

Block, Walter E. 2008. “Further Developments on the Issue of Social Justice in Baltimore” December 6;

Block, Walter E. 2008. “Block to Fok.” December 8;

November 6, 2008. Baltimore, MD. Loyola College Maryland, “Defending the Undefendable” and “Social Justice: A Critique.”;
November 12, 2008. Baltimore MD. Interview with Laura Vozella, Baltimore Sun;;,0,7454003.column
November 13, 2008. Baltimore, MD. Ron Smith Show, WBAL Radio AM1090, call in 410–338-6629;; Ryan Bogash, 410-338-6529,;;
November 16, 2008. New Orleans, LA. Debate with Amatai Etzioni on government bailouts. Malaka Gharib | interview producer | NEWS; AL JAZEERA ENGLISH | Washington, D.C. mobile 562 857 8298; 202 496 4671;;
November 18, 2008. Washington D.C. Interview on Baltimore experience with Andy Guess, Inside Higher Ed, 202-659-9208 x104 (office), 301-512-9754 (cell);;
November 20, 2008. Ron Smith Show, WBAL Radio AM1090, call in 410–338-6629;; Ryan Bogash, 410-338-6529,; with Tom DiLorenzo;
November 22, 2008. New Orleans. Interview with Steve Heath of the Maroon, male-female, black-white wage gap;
November 23, 2008. New Orleans Interview with James Gill of the Times Picayune; male-female, black-white wage gap;;;
November 26, 2008. New Orleans. Interview with Kevin Griffin, WBOK, radio 1230 AM, male-female, black-white wage gap; Kevin Griffin, 1639 Gentilly Blvd, New Orleans, LA 70119, 504.942.0106, Ofc; 504.942.0309 Fax; 504.722.0498 Cell; Blaine Bondi, Paul Boulieau

Burgaleta,, 2012; Cooijmans, 2003; Eysenck,1981; Hedges and Nowell, 1995; Lehrke, R. 1997; Lubinski and Benbow, 2006; Lynn, et. al, 2005; Lynn and Irwing, 2004; Lynn, 2010; Machin and Pekkarinen, 2008; Mills, 2011; Murray, 2011

Burgaleta, Miguel, Kevin Head, Juan Álvarez-Linera, Kenia Martínez, Sergio Escorial, Richard Haier, Roberto Colom. 2012. “Sex differences in brain volume are related to specific skills, not to general intelligence.” Intelligence; Vol. 40, Issue 1, January–February, pp. 60–68;

Cooijmans, Paul. 2003. “Sex differences in intelligence.”
When it comes to the question whether or not there is difference in mean IQ between males and females, Jensen basically says no, after having considered a large amount of evidence. Eysenck is a little bit more skeptical and points out that the usual assumption of equal IQ of the sexes may be flawed. Based on data also mentioned by Jensen (R. Lynn, 1994, Sex differences in intelligence and brain size: a paradox resolved), Eysenck suggests 4 IQ points as a conservative estimate of the difference (favoring males). Lynn, on his home page, simple states in adults the difference is about 4 points.
Both Jensen and Eysenck indicate that the question is hard to answer, as IQ tests like Stanford-Binet and WAIS have traditionally been constructed to show no sex difference in total score, by leaving out or counterbalancing items that show sex differences. Such tests therefore are not capable of measuring a possible difference between the sexes.
I myself cannot observe a mean difference directly as I only deal with high-range tests. I will return to this point further on with regard to the variance difference.
The male variance in IQ is greater than that for females; Jensen says this difference is greatest in math and spatial ability. In math the male variance is 1.1 to 1.3 times greater (he does not give the difference for total IQ or g).
In the high range, my own observation to date is that at or above the 98th percentile there are about twice more males than females, while at or above the 99.9th percentile there are about 15 times more males. Trying to make this fit in terms of standard deviation (variance is the square of the standard deviation by the way), I find that when the male and female mean are both IQ 100, the male standard deviation (SD) must be about 33% greater than the female SD. However, when a mean difference of 5 points in favor of males would exist, the male SD would only need to be about 11% greater. I don’t know which is true (or if the truth lies in between) and will not be able to verify it myself as I only deal with high-range tests. I must say though that an SD difference of 33% seems unlikely.

Eysenck, H.J. 1981. Race, Intelligence and Education. Maurice Temple Smith Ltd

Hedges, Larry V. and Amy Nowell. 1995. “Sex differences in mental test scores, variability and numbers of high-scoring individuals.” Science. Vol. 269, No. 5220, July, pp. 41-45;

Lehrke, R. 1997. Sex linkage of intelligence: The X-Factor. NY: Praeger.

Lubinski, D., & Benbow, C. M. 2006. Study of mathematically precocious youth after 35 years. Perspectives on Psychological Science, 1, 316 – 345.

Lynn, Richard, Adrian Raine, Peter H. Venables, Sarnoff A. Mednick, and Paul Irwing. 2005. “Sex differences on the WISC-R in Mauritius.” Intelligence, Volume 33, Issue 5, September-October, Pages 527-533;

Lynn, Richard and Paul Irwing. 2004. “Sex differences on the progressive matrices: A meta-analysis,” Intelligence, Vol. 32, pp. 481–498;

Lynn, Richard. 2010. “Sorry, men ARE more brainy than women (and more stupid too!) It’s a simple scientific fact, says one of Britain’s top dons.” Mail Online, May 8;;

Machin, Stephen and Tuomas Pekkarinen. 2008 . “Global Sex Differences in Test Score Variability.” Science. Vol. 322, no. 5906, pp. 1331-1332, November.

Mills, Michael. 2011. “How Can There Still Be a Sex Difference, Even When There Is No Sex Difference? Why men may be more variable on some traits.” Psychology Today. Jamuary 26;
“This finding of greater male variability in IQ scores has been replicated with many different populations and in more modern times. (See, for example, Hedges and Nowell (1995); and in particular see the appendix of Lubinski and Benbow (2006): Study of mathematically precocious youth after 35 years.)
You may recall that Larry Summers was forced to resign as President of Harvard University when many people simply misinterpreted his remark that males are more variable than are females on many traits:
It does appear that on many, many different human attributes-height, weight, propensity for criminality, overall IQ, mathematical ability, scientific ability-there is relatively clear evidence that whatever the difference in means-which can be debated-there is a difference in the standard deviation, and variability of a male and a female population.
Most of his critics misunderstood his remarks and presumed that he was suggesting that males are on average more intelligent than females. Or, if they understood him correctly, some may have found it interesting that there were more intellectually deficient males than females, but the sex ratio at the other tail of the distribution was less palatable. That is, they may have committed the morallistic fallacy — the assumption that if something is morally objectable, either on its face or in its possible misinterpretation or misuse, it cannot be factually correct.
However, if it is simply a fact that males are generally more variable than are females on many traits, why is this true?”
Murray, Charles. 2011. “A big step forward in understanding male-female cognitive differences.” The American Enterprise Blog; the online magazine of the American Enterprise Institute; December 6;


4:47 pm on February 4, 2018