The healthcare system is one of the most important sector in social area, especially because it has a great influence over the health status of the population (measured by life expectancy at birth). Furthermore, the healthcare system is a major consumer of human, material and financial...

This paper brings into attention a new method for analyzing renewable energy investments efficiency, a procedure called Principal Component Analysis. Authors aim to provide an adequate background for this method, before applying it to a set of data concerning renewable energy. The paper begins...