It is quite simple, really. In your model, the average channeler lies on 50, and the strongest possible channeler will lie on 100. Therefore, on your model, the strongest possible channeler is only double the strength of the average channeler. This is completely inconsistent with the text.

Instead, we see that the vast majority of channelers are very weak, and that everyone we see as being average strength channelers are actually very strong channelers. Even the normal Aes Sedai.

So, we know that 37.5% of women are weaker than Dagian who is say a 10 on the strength scale. Then, 12.5% of women fall between Dagian and the average woman - who is say a 15 on the strength scale.

That means, in this simple example, half of women fall below 15 which is still below the average Aes Sedai strength of 20. So this half of all women would include the Kin and all other women who are even weaker than Dagian, as well as weak Aes Sedai who fall above Dagian, but still below the average Aes Sedai strength.

To continue this example, we can then say that 62.5% of women fall below 20 - which is the average Aes Sedai strength. That would mean that 1 woman in 3 is stronger than the average Aes Sedai.

So you can see that to get to women like Nynaeve you are talking about 4 or 5 standard deviations from the mean - if the mean is 15 and Nynaeve is on 75.

Nynaeve appears to be 1 in 10 000 in terms of strength, so how many standard deviations from the mean would that be? I forget and I don't have my old textbooks handy. 3 standard deviations includes something like 97.5% of cases, and 4 standard deviations something like 99.95 of all cases. So Nynaeve might even be 5 standard deviations from the mean.

The point is, you cannot view the mean as being 50 on the strength scale. Because then you limit the strongest possible woman to being only double as strong as the average woman - which is refuted by the examples in the text.

Unless you take Egwene and Elayne to be of average strength - which is ridiculous, as they are among the strongest women in the Tower for 1000 years.

This Bell Curve cannot be centered on 50 strength, because RJ has stated that the vast majority of channelers in the Age of Legends were fairly weak, with only rare individuals being of great strength. It is the sheer numbers of channelers that allowed so many strong individuals to exist, because even though they were a very tiny percentage of the overall channelers, this small percentage still amounted to hundreds of thousands of channelers. Those who weren't of great strength, simply chose not to become Aes Sedai.

Remember, if 3% of the population could learn to channel, out of 5 to 10 billion or so that means around 100 million channelers.

And yet, according to RJ the number of Aes Sedai numbered in the hundreds of thousands to the low millions. So that's only about 1% of all possible channelers. The strongest 1%. And the Forsaken were probably the strongest 1% out of that 1%. Really the best of the best category.

So clearly, if you take the entire channeling population, the Bell Curve is centered far closer towards the bottom than to the top.