This paper estimates models of output, price and total inventory in va
rious manufacturing sectors that allow inventories at different stages
of fabrication to exert independent influences. The hypothesis tests
generally reject the hypotheses that inventories are irrelevant or can
be aggregated across stages of fabrication in the output and price mo
dels. The hypothesis that raw materials and work-in-process are irrele
vant is rejected in about half of the output and price model. In two-t
hirds of the industries, inventory behavior is independent of the comp
osition of stocks inherited from the previous period.