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The population is ___________ in size (growing, shrinking, or stable)
Lecture Quiz #4
Demography
• Demography is the science of measuring the
important phenomena that collectively provide
numerical descriptions of a population
– the number of individuals within it
– their birth rates and death rates
– movements of individuals between populations of the
same species
– the change in the number of individuals through time
N
now
= N
past
+ B – D + I + E
• N = population size (number of individuals)
• B = births (aka, natality)
• D = deaths (aka, mortality)
– the “flip” side of mortality is survival
• I = immigrants
• E = emigrants

2
Ages , or stages
• When information is assembled about a
population, this information is usually
arranged in a manner that indicates how
individuals of different ages (or stages )
contribute to the population as a whole
• These compilations of age- or stage-
specific data are called life tables