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).
Notice that in this case (as in many cases), population does not refer to people, but to bags of potato chips. To be concise, researchers often use symbols in place of words. Greek letters are usually used when referring to populations (the entire group being studied, from which a sample or samples will be drawn).