How much slack was there in the Chinese economy prior to its economic reform of 1978?

The existence of economic slack or inefficiency is a common phenomenon of economies that operate under mandatory central planning. It implies that the economy operates in the interior of its set of production possibilities and not on its frontier. It also implies that output can be increased without any increase in the inputs if the constraints which prevent the economy from operating on the frontier in the first place are removed. Thus, there is "surplus potential output" that is not directly observable and cannot be identified by conventional analysis of the relationship between inputs and output alone. The objective of this study is to attempt to identify and estimate the surplus potential output in the Chinese economy prior to its economic reform in 1978. This will help answer the question of how much of the Chinese economic growth since 1978 can be attributed to the reduction and elimination of the pre-existing economic slack. This question is important because the increase in output due to the reduction or elimination of the economic slack can only take effect once and cannot be continuing. It will also affect the attribution of the sources of Chinese economic growth. Our investigation suggests that a reasonable estimate of the magnitude of the surplus potential output of the Chinese economy on the eve of its reform is approximately 50% of the actual realized output in 1978.