A doctor told me that cephalic index can be used to measure human intelligence, is it true? I am roommates with a maxillofacial surgeon. He told me that during his studies he read that cephalic index can be used to measure intelligence.

And he further explained that as Africans and women have smaller brains according to cephalic index, so they are less intelligent than Caucasian and Asian men.

I just want to know how much of this is true, if any? And please explain.
No, the index and its correlation to intelligence is not strong.

See the medchrome.com description on cephalic index:


  
  The underlying assumption of craniometry is that skull size and shape
  determine brain size which determines such things as intelligence and
  capacity for moral behavior. Empirical evidence for this assumption is not very strong.
  Cephalic index consistently produced a very low or negative correlation with mental ability.
  


See also this article on Smithsonian.com: Why Brain Size Doesn’t Correlate With Intelligence

Healy and Rowe (2007) provide a critique of comparative studies of brain size.


Healy, S. D., &amp; Rowe, C. (2007). A critique of comparative studies of brain size. Proceedings of the Royal Society of London B: Biological Sciences, 274(1609), 453-464.