2 demography bioepi lab

demography

science of populations

population size

total number of individuals in a population

population structure/composition

measurable characteristics such as age, sex, and marital status

count

total number of occurrences of a demographic event in a specified amount of time

ratio

represents the relative size of 2 quantities

proportion/percentage

specific type of ratio where the numerator is part of the denominator

rate

measure change over time

median age

age that divides the population into two equal halves

population pyramid

graphical representation of the age and sex composition of the population at the same time

age-dependency ratio

ratio depends to the economically active population

0-14 and 65-over

number of dependents

15-64

economically active population

census

comprehensive data collection on all individuals in a country, typically conducted every 5 years

de jure method

counts residents based on where they are legally registered

de facto method

counts individuals based on their physical presence at a specific time

sample surveys

data collected from a subset of the population

registration systems

ongoing record of vital events and other societal indications

population distribution

describes the spread of populations across geographic areas, shaped by physical, social, economic, and political factor

population density

the average number of people per unit area

crowding index

calculated by dividing the total number of people in a household by the number of rooms

expansive pyramid

wide base, indicating a young population

constrictive pyramid

narrow base, indicating an aging population

stationary pyramid

rectangular shape indicating stable population growth

population size

refers to the total number of individuals influenced by birth rates and death rates

natality

birth rate in a population

mortality

death rates in a population

migration

immigration and emigration of individuals

population size estimation

estimating changes in apopulation size based on fertility, mortality, and migration rates