Early detection programme: Synonymous with screening studies.

Early warning system: A term used in disease surveillance for any procedure designed to detect as early as possible any departure from usual or normally observed frequency of phenomena. For example, in developing countries, a change in children's average weights is an early warning signal of nutritional deficiency. [Canadian Medical Association, 2002, 166, 1–2.]

EBM: Abbreviation for evidence-based medicine. Ecological fallacy: A term used when spatially aggregated data are analysed and the results assumed to apply to relationships at the individual level. In most cases, analyses based on area-level means give conclusions very different from those that would be obtained from an analysis of unit-level data. An example from the literature is a correlation coefficient of 0.11 between illiteracy and being foreign-born calculated from person-level data in the USA, compared with a value of ―0.53 between percentage illiteracy and percentage foreign-born calculated from summary state summary statistics. [Statistics in Medicine, 1992, 11, 1209–24.]

Ecological statistics: Procedures for studying the dynamics of natural communities and their relation to environmental variables. [Gotelli, N. J. and Ellison, A. M., 2004, A Primer of Ecological Statistics, Sinauer Associates Inc.]

Ecological study: A study in which the units of analysis are populations or groups of individuals rather than individuals. Used widely in epidemiology, despite their methodological limitations (see ecological fallacy), because of their low cost and convenience. [American Journal of Public Health, 1982, 72, 1336–44.]