Lecture 4 Flashcards
What is human demography (HD)?
HD studies changes in population size, structure and geographic distribution
(HD) Changes in population size, structure and geographic distribution are the result of?
fertility, mortality, and migration
why should health researchers care about demography and factors that affect population dynamics?
- demography
- economic, social, cultural factors as well as ecological and biological processes
- population health
All affect one another
HD is nourished by many different disciplines that analyse different aspects of the relationships between economic, social, cultural and biological processes that affect population dynamics such as: economic, sociology, history, biology, anthropology, etc.
what does an expanding population pyramid look like?
super wide at the bottom (young years) and gets super thin at the top (older years)
Stationary pyramid
relatively equal medium width throughout all years until late years very thin
- zero growth
constrictive pyramid
thinner at the bottom/younger years, wider in upper middle and relatively equal till latest years
- negative growth
how is population growth measured?
r = birth rate + [net migration] - death rate
net migration = immigration - emigration
crude mortality rates
m = (d/r) 1000
d = number of deaths during a year
r = number of individuals “at risk of dying”
age specific mortality rates
mx = (dx/Nx) 1000
d = number of deaths to individuals in the 4th age category during a year
N = number of individuals in the 4th age category
x = can be infants or other variables
mortality - two important parameters
- life expectancy
- average number of years remaining for an individual (e.g., life expectancy at birth) - age patterns of mortality
- age-specific mortality rates (fraction of cohort alive at the START OF THE INTERVAL)
- age specific mortality curves
what are some variability in mortality
sex differentials: women tend to live longer than males (with som exceptions) in contemporary industrialised populations
- geographic variation within populations
- variation between nations
life expectancy by country
World population as a whole = 73.4 years (76 females/70.8 males)
Longest life expectancy at birth - Hong Kong: total pop: 85.83 years, males:83, females:88.66
Shortest life expectancy at birth - Chad: 53.68 years, males:52.01, females:55.41
Developed countries: mortality started decreasing around 1920
biological regulation of human fertility
- variation in male and female fecundity
variation in female fecundity is critical for HD due to what factors?
- age
- energetics (pregnancy, childbirth, and lactation, require significant energy)
- lactation (Prolonged lactation can lead to longer inter-birth intervals which reduce the overall reproductive rate. Successful lactate can be influenced by health, nutrition, and SES, which affects child survival rates and maternal health)
- disease
- social environment
variation in female fecundity with age explained by changes in:
- ovarian hormone levels
- frequency of ovulation
- size of the follicle before ovulation
- thickness of the uterine lining
- fetal loss