demography pres 333
Post on 07-May-2015
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BY DR: MUHAMMED NAJEEBAssist: Professor
Community Medicine Deptt: LUMHS
DEMOGRAPHY
DEMOGRAPHY Demography is scientific study of
human population.
& Changes within them
POPULATION CHANGES
OR in Population Size & its Composition
in response to:
Birth Aging Death Migration
It focuses on 3 phenomena:
i Population size (# of persons in pop:)rapid growth, slow growth, population declineii Population Structure: / Composition: (Division according to characteristic) (E.g:- Sex structure, Age structure)ethnic, age, sex (also, how many are non-citizens)
iii Population distribution
% rural, % urban, % suburban. Also, how many citizens live overseas
Important ‘demographic processes’ include: fertility, mortality, marriage, education & social mobility.
Population Size:US, Florida & Leon country pop
1960 - 2000
1960 1970 1980 1990 2000
179,323,175 203,211,926 226,545,805 248,709,873 281,421,906
4,951,560 6,789,443 9,746,324 12,937,926 15,982,378
74,225 103,047 148,665 192,493 239,452
USFl
Ln
Population Structure: / Composition: (Division according to characteristic) (E.g:- Sex structure, Age
structure)ethnic, age, sex (also, how many are non-
citizens)
Males
Females
Population distribution
% rural, % urban, % suburban. Also, how many citizens live overseas
POPULATION DYNAMICS
No: of Live Births (B) No: of Deaths (D) No: of Immigration / In Migration
(IM) No: of Emigration / Out Migration
(OM)
Components of Population Change
(Population Dynamics)• Demographers rely upon the “Demographic Balancing Equation” to very simply and elegantly summarize population change:
Pop2 = Pop1 + B – D + IM – OM, where
Pop2 = Population at a later time period
Pop1 = Population at an earlier time period
B = BirthsD = DeathsIM = In-MigrationOM = Out-Migration
• The nature of population change is simple… changes can only occur through: 1) Births, 2) Deaths, or 3) Migration
Migration
Mortality
Fertility
REASONS OF MIGRATIONPUSH FACTORS:UnemploymentFamineWarPolitical or Religious harassment
PULL FACTORS:Attracts the MigrantsBooming economyFavorable Immigration laws.Free Agricultural Land
Population Growth Natural Increase (NI)
NI(B-D)+Net Migration(IM-OM)
Natural Increase:Surplus or deficit of births over death
Net Migration:
Net effect of immigration & emigration ( or )
Population Growth Rate(PGR)
Population is increased at a given period of time.
Effect of natural increase & net migration.
Expressed in % per year. Rapid PGR link to following many problems in less
developed countries.Hunger inadequacies in social / Health servicesPoverty i,e Transportation & communicationHigh IMR
Doubling Time “Rule of 70”
• Number of years it will take for population to double at current growth rate
Growth Rate Doubling TimeUganda 3.6% 19 yearsAfghanistan 2.5% 28 yearsIndia 1.3% 54 yearsUnited States .5% 140 yearsDenmark 0.0% --Russia -0.5% 140 years* (1/2)
70 ÷ Growth Rate = Doubling Time
Sources of Demographic Statistics
1. Census
2. National Survey
3. Registration of vital events
(Births, Deaths ,Marriages , Adoptions, Divorces &
separations)
4. Demographic Studies
END
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