Population: collection of persons alive at a specified point in time who meet certain criteria; collectively persisting through time despite members continuously changing
Count: absolute number of a population or any demographic event in a specific area at a specific time period
underlying building block of all demographic statistics
i.e. US census
Population Pyramid: display of population's age and sex composition
Rate: frequency of demographic events in population during a specific time period divided by the population "at risk" of the event occurring during that time period
number of occurrences per person-years of exposure to risk of occurrence
how common is an occurrence?
crude rate = entire population, specific rate = subgroup (those "at risk")
CBR(0,T) = number of births [0,T] per number of person-years lived [0,T]
CDR(0,T) = number of deaths [0,T] per number of person-years lived [0,T]
Growth Balance Equation: N(T) = N(0) + B[0,T] - D[0,T] + I[0,T] - O[0,T]
Natural Increase = births and deaths
Net Migration = in migrations and out migrations
Period Effects: consequences of historical change; broad, society wide events that impact all ages at point in time
Cohort: aggregate of all units that experience a particular demographic event during a specific time interval
person-year: measure of amount of time [0,T] an individual is alive during that period