> I am under the impression the 4 traits do map fairly well to the 'big 5'
Of the four axes of types on MBTI, and ignoring weak correlations, two each have a strong correlation to a Big-5 axis, one has a moderate correlation to an Big-5 axes, and the other has moderate correlations (one somewhat stronger) to two Big-5 axes (the weaker of which is one of the ones another MBTI axes has a strong correlation with.)
Of the four axes of types on MBTI, and ignoring weak correlations, two each have a strong correlation to a Big-5 axis, one has a moderate correlation to an Big-5 axes, and the other has moderate correlations (one somewhat stronger) to two Big-5 axes (the weaker of which is one of the ones another MBTI axes has a strong correlation with.)