Dictionary of Evidence-based Medicine.pdf

E
Ecological fallacy
This term is used to describe a spurious association due to inferring
relationships at the individual level from associations between variables at
the population level (Robinson WS (1950) Ecological correlations and the
behaviour of individuals. American Sociological Reviews. 15: 351-7).
Ecological study
An ecological study is one in which data are collected and correlated at the
population level rather than at the level of the individual. The unit of
observation in an ecological study is a group of people such as a school, a
factory, a city or a nation. An example of an ecological study is the study
of the relationship between average sales of beta-agonist inhalers and
deaths using data from different countries over the same time interval.
Such ecological studies can also be undertaken on the same population at
different times.
(The) Economic problem
The problem of allocating scarce resources to meet competing ends is
sometimes referred to as the economic problem or the fundamental economic
problem. It can be argued that, without scarcity, there is no need for
economics as a discipline.
Edgeworth box
The Edgeworth box is a graphical method for describing concepts such as
(i) interrelations between two markets; (ii) mutual gains and trade-offs;
(iii) Pareto efficiency. Figure 7 shows an Edgeworth box illustrating the
concept of Pareto efficiency.
The south-west and north-east corners of the box provide the point of
reference co-ordinates for subjects 1 and 2 respectively. The north-west
and south-east corners refer to the maximum amount of goods 1 and 2
(i.e. Ql and Q2) to be traded. The subjects have their own indifference