 The most fundamental criticisms came from Mahalanobis, who himself was working with a variant of it in 1951 and 1952.The criticisms were mostly around the model’s inability to cope with the real constraints of the economy; it’s ignoring of the fundamental choice problems of planning over time; and the lack of connection between the model and the actual selection of projects for governmental expenditure.Subsequently Mahalanobis introduced his celebrated two-sector model, which he later expanded into a four-sector version.