In particular, some (e.g., Anwar Shaikh) have suggested that since aggregate surplus value will generally differ from aggregate "profit", the former should be in fact treated as a mere "pre-condition" for the latter, rather than a full explanation of it. Using input-output data and empirical proxies for labour-values, Shaikh and Ochoa have provided some statistical evidence to show that, although no incontestable "logical" deduction may be possible of specific price magnitudes from specific value magnitudes, even within a complex model (in contrast to a probabilistic "prediction"), even a "93% Ricardian theory" of labour-value appears to be a better empirical predictor of price than its rivals.