Let E be a Banach space that is
complemented in its bidual by a projection P : E∗∗→ E. It is shown that E has
the Radon Nikodym property if and only if for every Radon probability
measure λ on the unit ball K of E∗∗ such that ω∗−∫Ax∗∗dλ ∈ E for every
weak∗ Borel subset A of K, the projection P is λ-Lusin measurable and
for every x∗ in E∗ the map x∗P satisfies the barycentric formula for λ on
K.