DEMOGRAPHY(STUDY OF POPULATION)Dr sanjeev sahu DPH1 Upgraded Department Of community medicineKing George's medical university, lucknow
DEMOGRAPHY-- is scientific study of human population.
-- is statistical study of human population with regard to their size & structure , their composition by age, sex, marital status & ethnic origin & the changes to these population like changes in their birth rate ,death rate & migration.
POPULATION is the number of person occupying a certain geographic area drawing substance from their habitat and interacting with one another.
HABITAT is natural home.(natural environment of an organism.)
DEMOGRAPHER commonly define population as a collective group of individual occupying a particular place at a given time.
. Three key word are involved in definition of population groupPlaceTime
DEMOGRAPHYIt focus on
(a) change in population size (growth or decline) (b) composition of population(age,sex,etc) (c) distribution of populationIt deals with`5 demographic processes
(a) fertility or natality (b) mortality (c) marriage (d) migration (e) social mobility scientific study of human population
Source of demographic data
In India main source of demographic data arePopulation census
National sample surveys
Registration of vital events
Adhoc demographic studies.
Importance of demography & demographic data Demographic data provide a basis for predicting future trends & making decisions.
It is also important for formulation, implementation & evaluation of plan ,policies & programs.
It guide to policy makers to make policies that can fulfill the needs of various sector of society such as young ,adult, & aged, unemployed, poor & various cultural group.
THEORIES ON POPULATION GROWTH AND DECLINE
MALTHUSIAN THEORY (THOMAS MALTHUS 1766-1834 )An assay n the principle of population theorized that population was uncontrollable & that it would.Argued that human population are inescapably caught in conflict between their need for food and passion between sexes. population he maintained increases geometrically (2,4,8,16,) while food supplies increases only arithmetically (2,3,4,5..)
MARXIAN THEORY(CARL MARX)Marx believed that problem was not primarily one of population but one of the ownership of the means of production and inequitable distribution of societies wealth.
DEMOGRAPHIC TRANSITION THEORY ( WARREN THOMPSON )
in 1929 the American demographer Warren Thompson observed changes in birth and death rates in industrialized societies over past 200 years or so and then formulated a model called demographic transition , that describes population change over time (demographic cycle).
DEMOGRAPHIC CYCLEit has 5 stages through which each country passes during course of time.
DEMOGRAPHIC CYCLECharacteristic & examples of different stages of demographic cycle
STAGE 1 2 3 4 5K/a HIGH STATIONARY EARLY EXPANDING LATE EXPANDING LOW STATIONARYDECLININGB R high unchanged(remains high) tends to fall Low Lower than DRDR high Begin to fallFalls further Low Low(higher than BR)DG (demographic gap) NarrowIncreasing Increased/start decreasingNarrow Reversal populationStationary Growing(Increasing rate)Growing (decreasing rate)Stationary decliningPopulation composition youngyoungyoungmixedageingEXAMPLEIndia till 1920AfricaIndia, ChinaAustria, Sweden Germany ,Hungary
*Components of population changeFERTILITY (BIRTHS) :Birth rate :number of live birth per 1000 estimated mid year population in a given year birth rate is the simplest indicator of fertility. birth rate (BR) =number of live birth during a year------------------------------------------- x1000 Estimated mid year populationMORTALITY ( DEATH ) :Death rate : number of death per 1000 of total mid year population in a particular place at a specified time
Death rate(DR) =-----------------------------------x1000Number of deathMid year populationMIGRATIONMigration is movement of people from one place to another ( within country or specified territory ) for the purpose of taking up permanent or semi permanent residence, usually across a political boundary.
Birth and death rates in IndiaDeclining birth rates Changes in government attitude
towards growthspread of educationincreased availability of contraceptionfamily planning programschange in marriage patterns
Declining death rateimprovement in maternal and child health servicesimproved immunizationdiarrhoeal and respiratory disease control programsreduction in infant and child mortality
Change in number of individual in a population pr unit time
When crude death rate subtracted to crude birth rate, the net residual is current annual growth rate, exclusive of migration.
Annual growth rate = crude birth rate crude death rate
On the basis of annual growth rate, population rating & its doubling time Modified from ,Source : principles of demography john Wiley (1969)
Annual growth ratePopulation ratingPopulation doubling time 0 stationary 139 year 0.5-1% moderate growth >70 year (139 -70) 1-1.5% rapid growth appox.50 year (70 -47) 1.5-2% Very rapid growth appox.40 year (47-35) >2% Explosive growth < 35 year
Annual growth rate(AGR)Annual growth rate = crude birth rate crude death rate look the example :*Note that this is exclusive of migration , as India has very little net migration rate (-0.005%).**annual growth rate of India (census 2011)..1.64 % But if we consider migration than.Decadal growth rate(DGR): Change in population over a decade**decadal growth rate of India (census 2011).17.64 %**decadal growth rate in Uttar Pradesh20.1%
Crude birth rate of India = 21.6 /1000 populationCrude death rate of India = 7 /1000 populationSoAnnual growth rate of India = 21.6 7 =14.6 /1000 populationOr =1.46 %
Migrant is a person who at the time of census is residing at a different place than his/her place of birth.
Marriage being the most common reason for females and employment for males .
Census 2001 total no of migrants 314 million in India
Immigration: People moving in to another country Emigration: People moving away from their home country.
*If you were to move to England, you would be emigrating from India and immigrating into England.*
Migration is movement of people from one place to another for the purpose of taking up permanent or semi permanent residence, usually across a political boundary MIGRATION
ROLE OF MIGRATION IN POPULATION GROWTHPush-Pull Factor
there are two things that affect population: Fertility/Mortality rate ,
:Migration rate . Population Growth rate = Rate of natural increase + net migration rateRate of natural increase = Birth rate Death rateDoubling Time: The amount of time it takes for a countrys population to doubleGenerally known as the Rule of 70:
70 / Population Growth Rate = doubling timeNet migration rate(India)
0.05 migrant(s)/1,000 population (2007 est.)
Rate of Natural Increase (%) How to calculate: look the exampleExercise:Population growth rate including migration: *net migration rate of india:0.05 migrant(s)/1,000 population (2007 est.)
CountryPopulation (Millions)Birth Rate per 1000Death Rate per 1000Natural Increase per 1000% Natural IncreaseIndia1,214,464,000(1.214 billion)23.08.514.51.45%
CountryPopulation (Millions)Birth Rate per 1000Death Rate per 1000Natural Increase per 1000% Natural IncreaseRussia140,367,00010.815.1
Country Rate of natural increase (%)net migration rate(%)Population Growth rate (%)India1.45-0.0051.45-0.005=1.44
*** population growth per 1000 is 14.45Hence, population growth per individual =14.45/1000So, population growth in %=14.45x100/1000 =1.445 %
Country Rate of natural increase (per 1000)net migration rate(per 1000)Population Growth rate( per 1000) India14.5-0.0514.45
GROWTH TREND OF INDIAPopulation growth of Indiaslower1921rapid
k/aGreat divide1991Slight fall2001Further fall2011****better nutrition & improved health care declined death rate more steeply than birth rate. This result in net gain in birth over death leading to rapid growth.
***recent data suggest decline in India population growth rate, India's population currently increasing at a