Exam 1 Flashcards
Demography
The study of populations
size and composition
age sex race ethnicity education spatial distribution
Processes that change size and composition
birth
death
migration
unions
formal demography
math and stats
population studies
interplay of demographic and non-demographic
variables
Balancing equation
N(t) = N(0) + B[0,t) – D[0,t) + IM[0,t) - OM[0,t)
Growth rate equation
birth rate-death rate + net migration rate
r= b-d+im-om
arithmetic (linear) growth
change by a constant number each period (year, for example)
geometric growth
growth by a constant ratio each period
exponential growth
growth compounds continuously (instantaneously)
rate of change is constant
population structure
- Relative distributions by age and sex
- Varies among populations and over time
- Affects observed numbers and rates of demographic events
- Important to consider structure in any analysis!
- Age-specific rates
Example: ASDR = #deaths at age A [0,t) / # person-years at age A[0,t)
Young age dependency ratio
Population 15 and under / population aged 18 to 64*
Old age dependence ratio
Population 65+ / population aged 18 to 64
Traditionally concerned with small populations
- Ethnographic data
- Skeletal remains
- Historical documents
- Genetic evidence
Subsistence strategies
How a population makes a living
* Foraging (hunting and gathering), horticulture, pastoralism, intensive agriculture,
industrial agriculture
* Amount of resources, environmental factors, and labor requirements shape
population size, density, social organization, etc.
Model of cultural systems
(cultural ecology)
ideology > social organization > economy/technology/population
foraging
10,000+ years ago
all human groups relied on foraging
Foragers for 190,000 years (95%) of our
existence as a species
Today - 250k foragers (0.005%)
foragers
Rely on naturally available
resources
Some combination of
plant &
animal foods
Mix varies with
environment
settlement and mobility
Move to resources
Seasonally & occasionally
Required in marginal
environments
mobile foragers
Don’t store food for long
Not enough or can’t be stored
But starvation and famine are rare
Subsistence agriculture (horticulture)
energy = human labor
Intensive agriculture
energy = non-human (animal) & human energy
Industrial agriculture
energy = non-human (fossil fuel), & human energy
Pastoralism
energy = depends, but always human & animal
domestication
Plants or animals that are different
from their wild ancestors or relatives.
result of domestication
Result: plant & animal species dependent on humans
for dispersal, reproduction and protection.
agriculture
Involves human efforts to modify environments of
domesticated plants & increase their productivity &
usefulness
weeding (removing competitors)
fertilizing soils
tilling land
Horticulture
“Garden cultivation”
Polyculture
Little surplus
KEY: Local inputs & human labor
only
Locally made tools
No irrigation, fertilization
Intensive agriculture
Investment of energy to gain an even
greater return in energy
Social Organization
Horticulture & Intensive Ag. = sedentary
Creates new political & social problems:
protecting resources (fields, etc)
resolving disputes
Descent groups own land
Usufruct rights
As long as you work it, it is yours (horticulture
Pastoralism
Animal husbandry
breeding, use & care of herd
animals
Two types:
Sedentary pastoralism
Dairy farming, ranching
Nomadic pastoralism
notations
- n=length of interval (often 1 or 5 years)
- x=exact age x
- Lower-case letters: an age/interval-specific measure or a measure
calculated for the life table - Upper-case letters: a measure totaled over several ages/intervals or
an observed measure
nNx
Observed mid-interval population
nDx
Observed number of deaths in interval
nMx
death rate between ages x and x+n
nAx
avg. person-years lived in interval by those dying in the interval
nQx
: prob. of dying between ages x and x+n
nPx
: prob. of surviving between ages x and x+n
lx
number left alive at age x
nDx
number dying between ages x and x+n
nLx
Person-years lived between ages x and x+n
Tx
Person-years lived above age x
e0x
Expectation of life at age x
life tables estimate…
both level AND age pattern of mortality
Life expectancy at birth
a common measure of level of mortality
Sex variation in mortality level
- e0 is higher for women
- Behavioral (smoking and alcohol consumption)
- Hormonal
- Estrogens enhance immunocompetence, androgens reduce it
- Some exceptions
- Contexts with high female infant mortality
- Alcohol consumption low, fertility high
- Contemporary small-scale societies
Level of mortality
- Life expectancy at birth
- Lower limit: about 20
- Cannot sustain much higher mortality given human fertility patterns
- Interpretation
- Prehistoric: 20-40
- Modern: 40-80 *greatest observed variation
- Contemporary small-scale: higher than prehistoric, but lower than
industrial
What causes level and age-pattern
variation?
- Proximate Causes
- Closest to or immediately responsible
- Ultimate Causes
- “higher-level” or cause of the proximate causes
Epidemiologic Transition
Describes changing patterns in morbidity and mortality by cause over time
Age patterns
- U-shaped
- Age patterns vary independently of level of mortality
- Geographical patterns persist even though level changes
- Difficult to ascertain from the past
- Use of model life tables in paleodemography (same issues as e0 estimates)
- Cannot easily determine sex of pre-pubescent skeletons
Modeling age patterns
siler model
Human mortality can be decomposed into 3 components
- Juvenile mortality
- Senescent mortality
- Residual mortality
Cause of death and age patterns
- Infant and early childhood
- Low today, but a large component of mortality in the past
- Undernutrition
- Infectious disease
Residual and senescent mortality
- Residual: Accidents, violence
- Senescent: Degenerative disease, chronic disease
heterogenity
variation in risks
crude death rate measurement
number of deaths during year / mid-year population
probability
occurrences / # trials, must be [0,1]
ratio
a/b
example: sex ratio = (N males/N females) * 100
How do we learn about
contemporary national populations? sources of data
- Census
- Civil registration
- Birth records
- Death records
- Marriage records
- Surveys
- Demographic and Health Surveys (DHS)
- American Community Survey (ACS)
- National Longitudinal Survey of Adolescent to Adult Health (AddHealth)
- Tax records
- Social Security records, Medicare/Medicaid records
Census
National enumeration of a population at the same time
De facto
- Counts people where they were found on day of census
de jure
Counts people where they usually live, regardless of where they are on
census day
Why take a census?
- Taxation
- Military conscription
- Social services
- Political representation
- Planning
- Denominator of many important measurements (population at risk)
United States Census
- Began in 1790
- 2010 Census
- First census without a long form (administered to 1 in 6 households,
questions about economics, etc) - Long form replaced by American Community Survey
- 2020 Census
- First census with Internet response option
Surveys
-cross sectional surveys
-longitudinal surveys
-focus
cross sectional surveys
- “snapshot”; repeated panel
longitudinal surveys
Follow up over multiple “waves” or rounds of observation/surveying, etc
focus surveys
- Group(s) of interest
- Nationally-representative
n is
length of interval
x is
exact age
