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