Definition of knell. 1  transitive verb. : 2  to summon or announce by or as if by a knell. 3  intransitive verb. 4  1 : to ring especially for a death, funeral, or disaster : toll. 5  2 : to sound in an ominous manner or with an ominous effect.
For the journal, see Demography (journal) . Demography is the statistical study of populations, including of human beings. As a very general science, it can analyze any kind of dynamic living population, i.e., one that changes over time or space (see population dynamics).
Epidemiologists study disease transmission. Vaccination for a virus. An epidemiologist may study public health crises in a given country. An epidemiologist may study car crashes as it relates to injuries. An epidemiologist may work with doctors and other health care workers to address specific health issues.View slideshow of images above.n epidemiologist may study car crashes as it relates to injuries. An epidemiologist may work with doctors and other health care workers to address specific health issues.