A standard demand made in connection with structural economic reform, ecological tax reforms and the like is that national product computation be corrected in order to obtain a ‘Green GDP’. Prices ought no longer to ‘tell the truth’ only in individual cases but also at the macroeconomic level, and take into account the scarcity of natural resources. This contribution analyses the chances of meeting this demand in practice. It is shown that the opportunities of obtaining information and the knowledge available are so limited that the statistical implementation of theoretical models has not been successful. This means that the informational problem is no longer a marginal issue but of a central nature and must influence the way theoretical models are set up
