Since we're on a new page, here's a summary for anyone interested:

Is there a difference in math performance?
Well, the title of the thread says no, and if you read the first few pages of the thread, you'll see people triumphantly celebrating the belief that there is no difference in performance.

Unfortunately, many scientific studies show otherwise. The difference is not in the average performance, but in the variance (the difference between the highest and lowest achievers). Here are three such studies:

1. The Hyde study
2. The PISA study
3. The Hedges study

Each of these, and others, showed a greater difference in variance among males than among females. Essentially, the data looks something like this:



This is an established scientific fact, shown with multiple studies. It's no longer up for debate. If you came in here thinking there was no difference between male and female math performance, you're just flat wrong.

What's causing this?
Two hypotheses have been proposed. Here's how science works: a hypothesis enables predictions about a system. If attributes of the system are not explained by, or do not fit the hypothesis, then the hypothesis must be modified or discarded. Let's see which hypothesis best fits the observed data.

Environment
Hypothesis 1: This is caused by environmental factors - basically cultural pressure and outright discrimination. This is a very appealing hypothesis because discrimination is wrong, so if you support this hypothesis you get to feel like you are righting a great injustice.

What does this hypothesis predict? Chiefly that as culture changes, the observed effect must change. In particular, a culture with less unjust pressure and discrimination should show a lower difference, and a culture with no injustice at all should show zero difference.

Does the data support this? No, not for variance. The PISA study, posted above, did find a decreasing difference in average ability, correlated to some measure of social justice. So we know that the PISA study works. But it did not show a decreasing difference in variance.

What else does this hypothesis predict? Constant pressure, in either direction, should cause constant movement. Imagine two children. One is encouraged to study music, the other is discouraged. We would expect the distance between these children, in terms of musical ability, to increase over time.

Does the data support this? No. While the Hyde study did show an increasing difference over a few grades, the effect hit a peak in the 8th grade and became chaotic each year after.

And there's another, more worrying problem: If boys are being encouraged, and/or girls discouraged, then we would expect that process to move the average, and not the variance. In fact, it's difficult to imagine any possible way to intentionally affect variance. Indeed, in experiments in which children are actively and intentionally privileged or discriminated against, such as Jane Elliott's famous experiment she observed that all of the brown-eyed children did worse and all of the blue-eyed children improved. That is to say, she saw a change in average, but not variance.

This hypothesis cannot explain the observed data. It must be rejected.

Evolution
Hypothesis 2: This is a normal part of our species, a result of the unique hominid evolutionary path, and an adaptation that helped our ancestors survive.

What does this hypothesis predict? For starters, the reason there is greater variance among males is because of a male mammal's lower inherent worth to the group. Imagine a group of almost any kind of mammal. If you kill off half of the males, the group will recover in a generation or two. The remaining males can easily pick up the slack. But if you kill off half the females, the group will not recover for many generations. What this means is that the process of evolution can safely cause greater variability among males - when evolution hits on a beneficial adaptation, great! But when it doesn't, there's no great loss if a male or two dies. Evolution rolls the dice much more liberally with males of our species. What this hypothesis predicts, therefore, is that we should see greater variance in other areas - not just in math performance.

Does the data support this? Yes. The PISA study is a good example. They found greater variance in geometry, reading skill, etc. In fact, this effect is seen even outside of academic performance. More males become rich in our society, but more males also become criminals. In almost any trait you care to consider, you'll find this effect.

What else does this hypothesis predict? This hypothesis is essentially extending sexual dimorphism to the brain. As anyone can see, males and females are different externally. The hypothesis predicts that there should be differences in the brain as well, and that the observed difference in math performance is one consequence of that.

Does the data support this? Yes. There are many studies that show that male and female brains are organized differently, storing information in different places and in different ways. This can actually be observed in action in functional MRI scanners.

So what does this mean for me, personally?
As an individual, already alive, it means absolutely nothing (except where society stereotypes you). The dice of your genetic heritage were thrown before you were born. For example, as a male, this scientific fact does not mean that I should be able to outperform and particular female on a math test. It turns out that girls perform better on reading tests. But that (also a scientific fact) doesn't mean that I'm going lose to a female on a reading comprehension test. My dice have already been rolled, and so have hers. I may well be a naturally better reader than her.

Should I feel bad because my gender has lower average reading scores? Certainly not. I am not my gender. I am not a bell curve. I am an individual. I have certain gifts and certain shortcomings that are seemingly random. Unless I'm very immature, and anchoring my ego and self-worth to my "gender team" this scientific fact is nothing more than an interesting attribute of my species.

Isn't this sexist?
No. Sexism is applying something that may actually be true of a population, to an individual. It is true that women perform better on reading tests. That isn't sexist. But if you disregard all the resumes of males and keep all the resumes of women, telling yourself "well, these guys can't read" that certainly is sexist. Because some of those males are definitely better readers than some of the females. You're hurting yourself if you fail to consider each person as an individual.

Sexism is something we should guard against, but our fear of it shouldn't blind us to facts. I would rather face the terrible truth about Santa Claus than take comfort in the fantasy. I would rather face the truth that men and women have different brains and different average abilities than to live in the fantasy that we're all the same.

So men are better?
Ridiculous. Anyone who would suggest that, or claim that I'm suggesting that is projecting some insecurity that they have about themselves. The better performance in reading tests among women doesn't translate to "women are better" either. This is just a really childish, ignorant way of thinking.

What's next?
Ken G will go through this post, select a sentence here or there, and post responses like, "so you're saying that Santa Claus has something to do with evolution." I ask that everyone keep in mind that I've gone out and researched this and presented a sound case, backed by solid science. If you look back through this long thread, you'll find that Ken G has posted nothing but his opinion, and even admitted twice that instead of supporting facts, he has only "common sense." But his comon sense is colored by a view of the world that is at odds with the data we have before us.