An investigation in which populations or groups of people, rather than individuals are looked at. Most of the studies referred to in this web page are such. An individual does not have a life expectancy, nor an income distribution, but a population, a city, state or country, does. Ecologic studies do not allow statements to be made about individuals, just about the population. A term referring to a gland that secretes its hormone directly into the bloodstream that flows through it, rather than through an opening into the intestine, as say the gallbladder, or pancreas does with digestive enzymes.
Adrenaline is another term for it.
A measure of inequality, usually applied to income. It is derived from a Lorentz Curve which plots the cumulative percent of income against the cumulative percent of income recipients. It is twice the area of the curve between what would be perfect equality and the existing distribution is the Gini coefficient. It is more sensitive to differences in the middle of the distribution, than to the ends. The cover term for the hormones made in the adrenal cortex, an example of which is cortisol.