The aim of this paper is to show which are developed countries (economic leaders), which are medium-developed countries, which are developing countries, and what are the factors that affect that country is a economic leader, has a strong economic impact and lead the world economy together with other leaders, and which factors influence that country is underdeveloped. The analysis will be conducted on a sample of 50 countries. Gross Domestic Product per capita (GDP p.c.), Human Development Index (HDI), unemployment rate and average monthly wage in the country have been taken for the development measures. For each economic leaders, middle-income countries or developing countries, factors that will follow, will be: investment in education as a percentage of gross domestic product, age of retirement, the average weekly working time in hours and the rate of natural increase in the country. The analysis will determine how some of these factors affect the development of the country and what impact each factor has on the development of the country. The paper set out two hypotheses, which were accepted. The first hypothesis is: ''The age of retirement is positively correlated with Gross Domestic Product per capita (GDP p.c.) and the human development index (HDI)''. The second hypothesis is: ''The average weekly working time in hours is negatively correlated with gross domestic product per capita (GDP p.c.) and the human development index (HDI)''.