Not to split hairs, but in terms of IQ, sensors are grouped in the average category (91-109), while intuitives are grouped higher.
Unlike what is assumed, however, it is generally believed that those with lower IQ develop their sensing skills as a way to compensate. IOW, personality doesn't define IQ. (KAIT)
It is also a subset of openness and little to do with the imagination/creative aspects of N/Openness (if memory serves me correctly). So there is a rather large correlation between abstract sub-traits and gF (I think), while gC seems to just be hanging about equally (although still gapped, with a preference for openness type traits - the willingness to learn and grow).
The reason why this doesn't manifest itself universally is because there is a huge overlap
despite the binomial distribution of S/N, and simply because Ss don't do any worse in the workplace, statistically speaking. Just like the N side, the STJs cannibalise the SFs and the STPs (NTJs doing the same to the other side) to become vastly over represented. If you normally distribute the factors, the correlation is about 0.3, I think, which isn't very significant. Course, when you segment the population into a 25/33-75/66 split, you are going to get a wider gap.
What is normally misunderstood is that while Ns are unique good at taking IQ tests, this is because all of the gF loaded tests require abstract thinking. By definition, N's will be better at it. What it doesn't note is that there are very few to no
success factors involved. Not money, not happiness... There is a correlation between IQ and wealth and a few others, but for the most part, very little.
*shrug*
The problems start when someone starts using these averages as something meaningful. Saying N's are smarter is like saying blacks commit more crimes. Statistically true (in some locations), but irrelevent except for research purposes. It is done to find information, to find causes and to find correlations. Applying it to individuals or groups isn't any better than building upon the same model as racism.

As you wish.