The view that real growth in the economy depends to a considerable extent even in the short run, and almost completely in the long run, on factors affecting supply rather than on effective demand. Supply-side proposals to increase economic growth could include measures such as the reform of tax systems to encourage investment and innovation, the reform of restrictive practices, improvements in the infrastructure of transport and communications, better training and more assistance with mobility for unemployed workers, and reforming social security systems to encourage labour supply. This is contrasted with the view in Keynesian economics that the main factor affecting economic growth is the level of effective demand.