I know this sounds absurd, but is there any pertinence to the idea of “the amount of one’s intelligence is proportional to the size of his/her head/brain”? Have there ever been any studies regarding this? Einstein looked like he had a fairly large head, and I think I remember hearing that his brain was studied after his death, and it was found to be abnormally large. Someone clarify this please.
No direct cite, but this has been studied since the 19th century. No correlation.
I’ve heard that it was the density of the folds in the brain that determined intelligence? The more folds in the cerebellum, the more knowledge ya have?
D.
If there is any real science out there, I don’t intend to argue it, but rarely have I seen a successful (academic or financial) man who had a small hat size comparable to what I quite often see in men who perform the more menial roles in society.
Be careful about how you define “big head,” too, as people often confuse size with shape. For instance, Europeans/Americans often think that Asians have big heads because their faces appear broader than those of Europeans, but the reality is that this is more often a shape issue. Many Asians have heads that are shorter from front to back and broader from side to side than Europeans/Americans. But many Europeans/Americans have very long heads and narrow faces that, reshaped, would be about the same size as Asians’. I say this because Asians have a reputation for high intelligence, and I’ve actually heard non-Asians say it’s because they have big heads and bigger brains!
I think there is a correlation, as I am extremely intelligent, but my wife says I am always big headed 
Intelligence and knowledge are two more or less independent qualities.
Einstein’s brain wasn’t particularly unusual. But as a counter example I offer Kerry v Bush.
To expand on the point noted in BobLibDem’s link, while Einstein’s brain was not noticeably larger than that of most European males of the period, it did have a unique (or rare) structure.
(On the other hand, no one has yet measured the volume or weight of the brains of either of the recent presidential candidates and aside from personal beliefs, we have no evidence of their relative intelligence, so there will be no more references to that sort of comparison in GQ.) [ /Moderator Mode ]
In Stephen Jay Gould’s The Mismeasure of Man, he points out in Chapter 3 that several of the 19th century scientists who argued over the relative intelligence of people in comparison to brain size had brains that were, themselves, no more than “average” (and a number of reputable thinkers were discovered to have quite small brains).