The growth of an economy can be attributed to many factors. Some economists believe that these variables may be exogenous, while others argue that they are endogenous. Yet other economists believe that growth comes from a combination of both of these types of variables. There are many theories that attempt to explain economic growth. Exogenous variables are the things that are taken as given in given economic theories and models and are not explained, while endogenous variables are those that can be explained and are affected by changes in the exogenous variables. Robert Solow, who was an economist at the Massachusetts Institute of Technology, developed a growth theory that stated that increases in savings, population, and technology would lead to economic growth in the long run, but that all of these had to continually increase , especially technology, to support long-term growth. or ultimately there would be diminishing returns and people would not improve their situation. In his theory these factors are taken for granted and do not explain how the economy grows. He was also the founder of growth accounting, which is a way of understanding how much productivity growth can be achieved from increases or decreases in capital, labor and technology. Robert Lucas and Paul Romer, who were also economists, were among those who took Robert Solow's theory to the next level. They noted that Solow did not explain exactly how this growth occurs. They all agree that in the long run you get an improvement and that increasing productivity without increasing inputs is what ultimately drives growth, this is called technological progress. Technological progress is created in many ways, which we will talk about now. If an economy invests in research and development, it is halfway through the education of its citizens, all the way to university, either fully, through subsidies, or by partially subsidizing those who can afford to pay a percentage of the cost of education. Another government policy is to promote certain fields of education, which include science, technology, engineering and mathematics, in order to have a supply of labor that the government and the private sector can employ to work on many development projects. research and development of new technologies. technologies, processes and other innovations. Indeed, it is in the interests of the economy as a whole that the government has and should continue its policies aimed at “encouraging innovation, because the development and diffusion of new products and new processes for manufacturing products are key determinants of economic growth in the long term" (Elmendorf, 2015, p. 164).