In complete markets the no arbitrage opportunity condition implies determin
istic relationships between the prices of derivative assets. These relation
ships are incompatible with the available data and with statistical inferen
ce. The aim of this paper is to reconcile risk neutral valuation and statis
tical inference. For this purpose we justify an approach based on a stochas
tic risk-neutral measure. (C) 2000 Elsevier Science S.A. All rights reserve
d. JEL classification: G13; C51.