Todays Topics

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Todays Topics

• Posters
• Mechanics of getting and manipulating Excel files
• Death rates, loose ends and notation
• Components of population change
• Periods and cohorts
• Lexis Diagrams
• Demographic Data
• Comparing Population Rates

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What Makes an Analysis Demographic?(1 of 2)

• Vital Rates
• Natality, Nuptiality, Mortality, Migration
• Health, Marriage, Employment
• Linkage of Vital Rates to Population Structure
• What if everyone stopped having children or lived
  to be 200 years old? (film Children of Men)
• Demographic Theories
• Easterlin Hypothesis size of cohort affects
  individual behavior
• Model life Tables

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What Makes an Analysis Demographic?(2 of 2)

• Key Methodological Innovations
• Life Table
• Standardization and Decomposition
• Differences in vital rates (births, deaths,
  migration between two populations is due in part
  to age composition (whos older/younger) and the
  rates at each age.
• Survival Analysis
• Classic vs the New

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How Many People Have Ever Lived on Earth?

• 75 percent of the people who had ever been born
  were alive in 1970
• What do you need to know to see if this is
  reasonable???

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RATES

• Number of deaths in 2000 (these are thetas ? in
  Hinde)
• Bostwana 29,100
• Sweden 49,339
• Russia 2,051,000
• Utah 13,042 (2002)
• Population sizes in mid-2000
• Bostwana 1,651,000
• Sweden 5,176,000
• Russia 145,491,000
• Utah 2,338,761 (2002)
• M-type mortality rates
• Bostwana 29,100 / 1,651,000 0.0176
• Sweden 49,339 / 5,176,000 0.0095
• Russia 2,051,000 / 145,491,000 0.0141
• Utah 13,042 / 2,338,761 0.0056

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Death Rates

• Will return to Q-type (cohort) death rates when
  we discuss survival models
• Assume m-type death rates
• Crude death rates
• Age-specific death rates

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COMPONENTS OF POPULATION CHANGE

• Three components
• Births
• Deaths
• Migration
• Population change occurs because people make
  transitions between states

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E(t)
Alive and in the population
Alive and in another population
I(t)
E(t)
D(t)
Unborn
Dead
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Alive
Dead
Sterile
Sterile
Sterile
Having Had No Children
Having Had 1 Children
Having Had 2 Children
Dead
Dead
Dead
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The demographic accounting equation

• Final pop
• Initial pop births deaths immigration -
  emigration
• P(tn) P(t) B(t) D(t) I(t) E(t)
• Natural change B D
• Net balance of migration I E
• Example
• Mid-1998 pop of UK 59,237,000
• Births mid-1998 to mid-1999 711,000
• Deaths mid-1998 to mid-1999 635,000
• Net balance of international migration 188,000
• Mid-1999 pop of UK 59,501,000

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PERIODS AND COHORTS

• Periods
• Time point or interval
• Period perspective looks at populations or
  subpopulations for a given year or for a series
  of years
• e.g. deaths to aged 90 in the US for 1900, 1910,
  etc.
• Cohort
• a group of people sharing a common characteristic
  followed over time
• e.g. the birth cohort of 1983, the 2001 marriage
  cohort
• Cohort perspective follows a cohort over time as
  they age

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(Survey in 1985)
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RATIOS

• Ratios
• Ratio is a number divided by any other number
• e.g. x/y
• e.g. sex ratio (no. of males / no. of females)
  k
• For the UK in mid-1998 sex ratio
• (29,128,400 / 30,108,100) 100 96.7
• For 2000 Utah------?

Age Total Males Females
Other ratios include 1 The dependency ratio 2
The child-woman ratio 3 Parity progression ratios
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Rates and Exposure

• Rate ( of events) / ( of person-years lived)
  k
• k is often 1000
• Number of person-years lived population at risk
• How are person-years defined?
• 3 people in a pop for 1 year
• Person-years 3 people 1 year 3
  person-years
• 3 people in pop for 1 year 1 person in pop for
  ½ year
• Person-years (3 people 1 yr) ( 1 person
  ½ yr)
• 3½ person-years
• Normally use mid-point pop (mean of start
  end-of-interval populations)

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Lexis Diagrams, Cohorts, and Social and
Individual Change
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Assume Rates affected only age Deaths occur
evenly within an age
Denominator M type MN Q Type TM Numerator M
Type PQRS Q Type TMWN But PQRSTMWN (usually)
maPm
The difference between M and Q is how you treat
those who died before the mid point of the year.
q (2m)/(2m)
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Sources of Data

• Vital Records
• Births, deaths, fetal deaths, marriages
• U.S. Census Records
• Genealogies
• Surveys

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Vital Records Data Source

• www.demography.utah.edu
• National Center for Health Statistics

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Census Data Source

• www.demography.utah.edu
• US Maps and how Utah stacks up
• Utah

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Sources of Data

• Vital Records
• Births, deaths, fetal deaths, marriages
• U.S. Census Records
• Genealogies
• Family Group Sheets
• Surveys

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Sources of Data

• Vital Records
• Births, deaths, fetal deaths, marriages
• U.S. Census Records
• Genealogies
• Surveys

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Surveys (1of 2)

• Sampling
• Sampling frames and generalizability
• Coverage - RDD
• Nonresponse -Total Item
• Prospective/longitudinal
• Retrospective/cross sectional
• World Fertility Surveys - often with illiterate
  respondents
• Demographic and Health Surveys

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Surveys (2 of 2)

• Who and How You Get It
• Self vs Proxy
• Identifiers to link to other data (SSN)
• National Death Index
• Mode of administration
• Questionnaire construction
• Length of survey
• Types of questions
• Factual or subjective

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Comparing Populations

• Whats the Problem?
• Apples and Oranges
• Why Bother?
• If the differences are real, helps to identify
  population and public health trends and problems

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Confounded

• Two populations have different crude death rates
  (m). Why are they different?
• Need to rule out the obvious age since it has
  a profound effect on mortality
• Even after ruling out age, can still be other
  things to rule out as well sex, race, etc.
• Start with age and then standardize population
  structures with respect to age

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Dealing with Age Confounding

• Direct standardization
• Age Standardized Death Rates (ASDR)
• Indirect standardization
• Standardized Mortality Ratio (SMR)

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Age Standardization

• Eliminate age-distribution differences
• Amx Pop A m-type death rate for age group x
• SPx Population exposed to risk of death in some
  standard population for age group x
• ASDR for Pop A

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What is the ASDR?

• What does this do?
• The expected deaths for population A if you
  assume you have the age-specific death rates of
  population A but the age-structure of a standard
  population

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What is the ASDR?

• Another way to state this
• ASDR is
• Crude Death Rate of Standard Population times the
  Comparative Mortality Factor

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Another Perspective The CMF
Exp Deaths in Std Pop if it had Pop A
Age-specific DR Actual Deaths in Std Population
(Crude Death Rate in the Standard Population)
ASDR
x
This is the Comparative Mortality Factor (CMF) or
Ratio of Death Rates Between Pop A and Std Pop
Deaths at age x in Std Pop
Total Deaths in Std Pop
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Move to Indirect Standardization
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Standardized Mortality Ratio (SMR)

• Why do we need this?
• The ASDR and CMF require that we know the
  age-specific death rates in Population A
• Often this is not available, is known with error,
  or is based on small samples
• The SMR handles this by asking
• What is the ratio of deaths in Pop A (which is
  usually known) to the the number of deaths we
  would have expected in Pop A if it experienced
  Age-specific death rates of the standard
  population?
• This requires we know the age distribution of
  Pop A and the age-specific death rates of a
  standard population. We will not know the
  age-specific death rates of Pop A

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Standardized Mortality Ratio (SMR)
Numerator Total Deaths in Population
A Denominator Total Deaths in Population A if
experienced age-specific
death rates of the
standard population
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What Standardization Relies Upon
If this ratio is similar across all age
groups, standardization works pretty well. If
not, standardization will not be ideal but at
least acceptable
This is theoretical because you wont know Amx in
SMR case
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What Do You Have?

• Direct Standardization
• Age-specific mortality rates of Pop A and Age
  Distribution of Standard Population
• Gives you actual rates
• Indirect Standardization
• Total deaths and age distribution of Pop A,
  Age-specific mortality rates of Standard
  Population
• Gives you SMR, a ratio

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Excel TablesExamples in Chapter 3
Note errors in spreadsheet
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