What are the key variables that measure the development disparity between northern and southern Italy?

Two crucial variables measuring the north-south divide in Italy are Human Development Index (HDI) scores and GDP per capita. The HDI, measured on a 0-1 scale by the United Nations, considers healthcare access, education, income levels, and living conditions. Maps show a clear gradient: the further south you go in Italy, the lower the development becomes. While southern regions like Calabria and Sicily score around 0.859, which appears underdeveloped by Western European standards, these scores remain relatively high globally, comparable to Argentina, Chile, or Turkey, and above the global average.