The<unk> , using cross-country data for 2005. The x-axis shows GDP per capita in 2005 international dollars, the y-axis shows life expectancy at birth. Each dot represents a particular country. The<unk>  is an empirical cross-sectional relationship between life expectancy and real per capita income. It is named after Samuel H.<unk>  who first described it in 1975.<unk>  studied the relationship for the 1900s, 1930s and the 1960s and found it held for each of the three decades. More recent work has updated this research.
Preston curve
Wells curve
Patlak plot
E/A ratio
Base curve radius
Mentzer index
Extraction ratio
Shunt equation