Porter cites research by Andrew Berg and Jonathan Ostry of the IMF, which shows the strong connections between having a vibrant middle class, lower inequality and the sustainability of economic growth. In countries with higher inequality growth comes in spurts which fizzle out, and there are sharp contractions. Having good income distribution is important according to Berg and Ostry, if the process of economic growth is to be sustained. This logic is also supported by the need for a strong middle class for consumer spending, to provide the demand that supports growth.