Mar 12: Demography, Labor Migration, Displacement Tiebout,
Charles M. "A Pure Theory of Local Expenditures." Journal of
Political Economy, Vol. 64, No. 5, October 1956, pp. 416-424.
[Library reserves] Frey, William H. Immigration and Internal
Migration "Flight from US Metropolitan Areas: Toward a New
Demographic Balkanization." Urban Studies, Vol. 32, No. 4-5, May
1995, pp. 733-757. [Library reserves] Florida, Richard. 2002.
Bohemia and economic geography, Journal of Economic Geography 2
(Jan): 55-71. [c-tools "Resource" section] Florida, Richard. 2009.
How the Crash will Reshape America. The Atlantic Monthly; March.
[online] see also: Myers, Dowell and Lee Menifee. "Population
Analysis," in The Practice of Local Government Planning, 3rd
edition, edited by Charles J. Hoch, Linda C. Dalton and Frank S. So
International City/County Management Association, 2000, pp. 61-86.
[Library reserves] excerpts from Bill Bishop, The Big Sort [link]
links: US Census:Geographical Mobility/Migration Migration Data and
Reports migration tables in the 2009 Statistical Abstract United
Van Lines 2008 Migration Study the American Moving & Storage
Association CS Monitor: "Patchwork Nation" Andrea Coombes, Retirees
Who Relocate Often Opt For Homes in Metropolita Areas, Wall Street
Journal, March 31, 2006. [link]
Slide 2
What is demography?
Slide 3
Fertility Mortality economic demography migration
Slide 4
- Be born - give birth - migrate - (attract a migrant) -
die
Slide 5
time space birth death Imagine a two time-space dimensional
world (one time dimension, one space dimension) migration college
Comes Home After college Moves to another city for job Moves to
retirement community birth The next generation is born
Slide 6
time space birth death Imagine a two time-space dimensional
world (one time Dimension, one space dimension) migration
birth
Slide 7
time space birth death Do you need to know the path or just the
start and finish? birth
Slide 8
Demography: the study of life EVENTS. Individuals are at risk
of experiencing these events.
Slide 9
The frequency of events: events happen at rates: number of
events of a specific type in a given time period
---------------------------------------------------------- Number
of people at risk of experiencing that type of event in the given
time period. Rate =
Slide 10
The frequency of events: events happen at rates: occurrence
-------------- exposure Rate =
Slide 11
EXAMPLE: CRUDE DEATH RATE Total number of deaths in a given
year ----------------------------------------------------------
Total population in that year CDR =
Slide 12
EXAMPLE: CRUDE BIRTH RATE Total number of births in a given
year ----------------------------------------------------------
Total population in that year CBR =
Slide 13
EXAMPLE: CRUDE BIRTH RATE (per 1,000 pop) Total number of
births in a given year
------------------------------------------------- Total population
in that year CBR =* 1,000
Slide 14
Total number of births in a given year
------------------------------------------------- Total population
in that year CBR = * 1,000
Slide 15
A comparison of: CRUDE VERSUS AGE-SPECIFIC RATES General
Fertility Rate Age-Specific Fertility Rate Number of Births
_____________ Number of Women ages 15 - 49 Number of Births to
women ages 20 - 24 ______________ Number of Women ages 20 - 24
Total number of births in a given year _______ Total population in
that year Crude Birth Rate
Slide 16
The Demographic Transition
http://www.geo.oregonstate.edu/classes/geo300/trans/demot.jpg
http://www.populationaction.org/resources/factsh
eets/images/demographicTransit_fs.jpg
Fecundity: The physiological capacity of a woman to produce a
child [a theoretical upper limit] Fertility : The actual
reproductive performance of an individual, a couple, a group, or a
population. [fecundity adjusted by social/cultural practices and
events, including birth control, nutrition, delayed childbirth,
etc.]
Slide 20
Slide 21
Demography: the study of life EVENTS. Individuals are at risk
of experiencing these events. Events occur in a temporal-spatial
context.
Slide 22
Right now, each of you can be located at a specific: T n time
(1 dimension) S n space (3-dimensions [x,y,z], or 2 on a flat
surface [x,y], such as a map or the earths surface) When you were
born, you were located at a specific: T 0 time S 0 space From these
two we can get: Your age: T n - T 0 Your net migration: S n - S 0
(and with more, intermediate time points, we could also determine
the specific legs of your migratory path to Ann Arbor)
Slide 23
-if we follow age groups (cohorts) over time, then this is
known as cohort data Here: randomly pick three every 10 years -
special case: if we follow the same individuals in a cohort over
time, then this is known as panel data - Here: pick the same three
people every ten years 19701980199020001970198019902000 BirthAge 10
Age 20 Age 30 BirthAge 10 Age 20 Age 30 Having data over time is
known as longitudinal data
Slide 24
"Give me the child at seven, and I will give you the man.
Example of a cohort study
Slide 25
Mortality
Slide 26
10 Leading Causes of Death in 2001 1. heart disease 2.cancer
3.stroke 4.chronic lower respiratory disease 5.accidents 6.diabetes
7.pneumonia/flu 8.Alzheimer's disease 9.kidney disease 10. Suicide
Source: Centers for Disease Control and Prevention (CDC), National
Center for Health StatisticsCenters for Disease Control and
Prevention (CDC), National Center for Health Statistics
Life expectancy of a village Of ten people 592 person-years
___________ 10 persons = 59.2 years
Slide 31
National Vital Statistics Reports, Vol. 54, No. 14, April 19,
2006
Slide 32
mortality in the United States, 1998
Slide 33
Death Rates, by Age Group, in the United States, 1998 Age 10 is
the safest time of life The first year of life is high risk Once
you get through the teenage years, the risk of death stops
increasing -- at least for a few years.
Slide 34
Slide 35
Life Expectancies (at birth) in the United States, in years (e
0 ) for the year 2001, by Race and Sex MaleFemaleTOTAL All
Races74.479.877.2 White75.080.277.7 Black68.675.572.2 Source:
National Vital Statistics Reports, Vol. 52, No. 14, February 18,
2004 33 url:
http://www.cdc.gov/nchs/data/dvs/nvsr52_14t12.pdfhttp://www.cdc.gov/nchs/data/dvs/nvsr52_14t12.pdf
Slide 36
http://www.cdc.gov/nchs/fastats/pdf/nvsr50_06tb12.pdf; FROM
http://www.cdc.gov/nchs/fastats/lifexpec.htmhttp://www.cdc.gov/nchs/fastats/lifexpec.htm
National Vital Statistics Report,Vol.50,No.6,March 21,2002 33 Table
12.Estimated life expectancy at birth in years,by race and
sex:Death-registration States,1900 28,and United States,1929 99
[For selected years,life table values shown are estimates;see
Technical notes.Beginning 1970 excludes deaths of nonresidents of
the United States;see Technical notes ]
Slide 37
Demography for planners? absolute population levels in the
future
Slide 38
but more importantly: The components of population. Demand for
services vary by age, sex, family status, immigration status,
etc.
Slide 39
Examples: demand for housing,roads, schools, child care,
special- needs housing.
Slide 40
Demographers thus speak of Age-specific rates (e.g.,
age-specific migration rates)
Slide 41
What is the implication for social policy (e.g., school
funding, job training, pension plans) of dramatic differences in
age-specific racial/ethnicity composition in places like California
and Florida?
Slide 42
US Census 2000 (SF3) TM-P017. Median Age: 2000 Source: American
FactFinder Thematic Mapping
Slide 43
The basic components of demographic change: Components of
Change: births, deaths, migration Example: Population 2000 =
Population 1990 + Births - Deaths + Inmigration - Outmigration Or P
t+10 = P t + B - D + IN - OUT Often you only know net migration, so
this becomes P t+10 = P t + B - D + Net Migration You can turn this
formula around to solve for Net Migration: Net Migration = (P t+10
- P t ) - (B - D) Population change Natural increase
Slide 44
Example: If starting Population P t = 100,000 Ending population
P t+10 = 150,000 Births in time period B = 30,000 Deaths D = 20,000
Then... Net Migration = (P t+10 - P t ) - (B - D) Net Migration =
(150,000 - 100,000) - (30,000 - 20,000) = 50,000 - 10,000 =
40,000
Slide 45
Panel data is the ideal data for migration studies: (following
the same people over time)
Slide 46
Panel data is the ideal data for migration studies: (following
the same people over time) Unfortunately, however, we dont often
have panel data. From the U.S. Census form, there are two key
questions of interest for migration studies: 1) Where were you
born? 2) Where did you live 5 years ago? (not a great measure of
migration over ones lifetime, but a start)
Slide 47
1) Where were you born? 2) Where did you live 5 years ago?
Slide 48
Slide 49
Source: US CENSUS American FactFinderUS CENSUS American
FactFinder 1) Where were you born?
Slide 50
Source: US CENSUS American FactFinderUS CENSUS American
FactFinder 2) Where did you live 5 years ago?
Slide 51
A challenge: how to represent data on migration? ANSWER:
Simplify: Show only selective moves Show only the major flows
(moves by many people) Show only long-distance moves (e.g.,
interregional)
Slide 52
Visually Representing Migration Flows: the Migration of
Scientists and Engineers, 1982 - 1989 (single, before-after flows;
only crossing regions)
Slide 53
Visually Representing Migration Flows: looking just at those
scientists and engineers who worked in the Pacific Region in
1989.
Slide 54
Visually Representing Migration Flows Regional migration, the
break-up of states and geopolitical realignment are changing the
shape of Africa. The continent is pulling apart and reforming under
the combined effects of demography, massive urbanisation and
economic, military and religious ambitions. The conflicts and
population movements rarely fit into a pattern based on the state,
but a confused picture is emerging on which the continent's new
frontiers are being drawn. Three main territorial groups are taking
shape. The first comprises the two ends of the continent, the
second the war zones in the Horn of Africa, the Great Lakes region
and the Congo. The third is emerging under the impact of the
internationalisation of trade and new ways of exploiting resources.
http://MondeDiplo.com/m aps/africambembemdv51
Slide 55
Map-Making Workshop at Sciences Po (L'Institut d'Etudes
Politiques de Paris) http://www.ttc.org/maps/migra.htm
Slide 56
Map-Making Workshop at Sciences Po (L'Institut d'Etudes
Politiques de Paris) http://www.ttc.org/maps/winte.htm#Top
Slide 57
Population Forecasting: from simple to complex (in each step,
you are using more information about the past and existing
population) 1. simplest: assumes it stays the same 2. linear
increase (could use trendline) 3. exponential increase (go to Excel
file on growth rates)Excel file ----------- 4. age-specific changes
(cohort-survival analysis using matrix algebra)
Slide 58
The Cohort-Survival Method (taking the age distribution of the
population into account) Or more specifically: Age-specific
fertility and Age-specific mortality. Cohort survival: how each
cohort survives. use matrix algebra to figure it out. Remember:
COHORT = AGE GROUPS
Slide 59
Why use cohorts? Because one can have more accurate estimates
of fertility, mortality, migration (and thus population levels) if
one breaks the population down into cohorts, since behavior is
often age-specific. (e.g., cohort survival rates) as distinctive
from crude rates (e.g., mortality).
Slide 60
So, each member of a specific age-cohort (e.g., 20 - 30 year
olds) is at risk of dying based on age-specific mortality rates. *
some people survive into the next cohort * others die so: persons
in the next age group = persons in this age group * survival rate
(the models are descriptive, not explanatory, since no causal
inferences are made about WHY population is increasing)
Slide 61
In addition, each female member of a cohort is at risk of
giving birth. The chances of this are based on age-specific
fertility rates. Generally these are highest in the age 20-30
cohort. so, for each age group, each person is "at risk" for either
giving birth or dying. (or also moving -- but we will only include
migration in the analysis later)
Slide 62
AND WHY DO WE USE MATRICES, IF THEY SEEMS SO COMPLICATED? IT
GIVES US THE OPPORTUNITY TO INCLUDE IN A SINGLE EQUATION BOTH
AGE-SPECIFIC BIRTHS AND DEATHS.
Slide 63
Use Matrix algebra to estimate population where P1 is the new
population level (by age) and C is the matrix (the sum of the
Survival and Birth matrices, S and B). C is the components of
change (here just B and S) In general, where n is the number of
time periods into the future. (the trick is to raise the components
of change matrix to the n power).
Slide 64
Migration: Adding the Migration Component Where M is net
migration See the Oppenheim reading for details
Slide 65
Question: How do you decide the optimal allocation of public
services? HINT: look at your feet
Intermediate variable dependent variable Assumes cause-effect
flows this way -->>
Slide 87
Slide 88
Slide 89
Direct effect of diversity on high- tech Indirect effect --
mediated via talent
Slide 90
Slide 91
No place in the United States is likely to escape a long and
deep recession. Nonetheless, as the crisis continues to spread
outward from New York, through industrial centers like Detroit, and
into the Sun Belt, it will undoubtedly settle much more heavily on
some places than on others. Some cities and regions will eventually
spring back stronger than before. Others may never come back at
all. As the crisis deepens, it will permanently and profoundly
alter the countrys economic landscape. I believe it marks the end
of a chapter in American economic history, and indeed, the end of a
whole way of life.
