Last Updated: March 15, 2011

How to count

Counts are at the core of epidemiology: we count the people who develop disease in particular years and particular places; we count their life style habits and familial antecedents. The concepts of counting health related events evolved over time; this evolution can be followed in background historical papers and in milestones papers. These concepts take into account how the events occur over time, in two ways, their cumulative frequency across time or the speed (or force) at which they have impact on a population. Several types of counts are considered, e.g., risk and rates, prevalence and incidence, as well as epidemic curves. Also included is an intriguing model in prevention of diseases, proposed by Geoffrey Rose, as well as by Sully Ledermann: that we should aim at reducing poor health related habits in the whole community, not just of people who have extreme levels of a risk factor.

Background publications


Morabia A (2004) Epidemiology: An epistemological perspective. In History of epidemiological methods and concepts , Morabia A (ed) pp 1-126. Birkhäuser: Basel , chapter 2

Eyler JM (2002) Constructing vital statistics: Thomas Rowe Edmonds and William Farr, 1835-1845. Morabia A (ed) pp 1-126. Birkhäuser: Basel , pp. 149-58. Older version in SPM.

Eyler JM (2003) Understanding William Farr's 1838 article "On prognosis": comment. Morabia A (ed) pp 1-126. Birkhäuser: Basel , pp, 195-198

Farr W (2003) "On prognosis" by William Farr (British Medical Almanack 1838; Supplement 199-216) Part 1 (pages 199-208). Morabia A (ed) pp 1-126. Birkhäuser: Basel , pp. 159-178. Older version in SPM, part one and part 2.

Gerstman BB (2003) Comments regarding "On prognosis" by William Farr (1838), with reconstruction of his longitudinal analysis of smallpox recovery and death rates. Morabia A (ed) pp 1-126. Birkhäuser: Basel , pp. 183-190. Older version in SPM.

Hill GB (2003) Comments on "On prognosis" by William Farr (British Medical Almanack 1838; Supplement 199-216). Part 2 (pages 208-216). Morabia A (ed) pp 1-126. Birkhäuser: Basel , pp. 179-182. Older version in SPM.

Key papers