DEMOGRAPHIC INDICATORS

Assoc. Prof. Petko Salchev, MD, PhD

The science of demography

„Demography” comes from demos – people and grapho – to write

Demography is a science dealing with types, methods and nature of population reproduction and factors affecting this process

Structure of the demographic science

Demographic theory Pure (formal) demography Analytic demography Historical demography Sociological demography

The demographic cycle

Stationary stage Early growth stage – characterized by a decline in

mortality and unchanged birth rate. Late growth stage – mortality continues to decrease,

but there is also a tendency for a decrease in birth rate, although still higher than mortality.

Stationary stage – characterized by low levels of birth rate and mortality.

Decline stage – birth rate lower than mortality.

Types of stages in Bulgarian population

Late growth stage

Stationary stage

Decline stage

Early growth stage

Population and population reproduction

Population, people – natural, historically set and constantly renewing itself in the course of life sum of people, the fundamental material component of human society

Population reproduction – this is one of the main processes of reproduction of society and represents a probability process, formed by a mass of random single events of birth and death

Reproductive behavior

Psychic regulator of behavior, personal predisposition governing the harmonization of a stream of activities, subject to positive or negative attitudes towards the birth of a given number of children

Readiness for a certain outcome of a walk of life, the acceptance from the individual of the necessity for giving birth to a given number of children

Main groups of demographic indicators

According to complexity:– simple – reflecting a count (population, births, etc.)– complex – expressing ratios (birth rate, mortality, etc.)– integral – the integration of several health events (life

expectancy, healthy life expectancy, etc.)

According to the type of study subject:– static – number, composition and structure of the

population in a given moment– dynamic – related to vital processes in human life or

population transitions in territory and time.

Indicators of population static

Population number Average yearly population number

Р0 + Р1

Р= -----------------2

Where Р0 is the population number at the beginning of the year, Р1 is the population number at the end of the year

Population number

Present population according to address registration (Population de fait)

Population according to place of residence (Population reference)

Risk exposed population (Population exposee ou risque) – the population with the highest probability of occurrence and development of a certain disease

Demographic transition Stages

Traditional – characterized by high and balanced levels of birthrate and mortality

Transitory – characterized by diminishing the level of mortality while keeping the birthrate

Stable – characterized by low and balanced birthrate and mortality

Population ageing – characterized by a growing proportion of aged people as a result of a lowered birthrate and higher life expectancy

Depopulation – characterized by high migration and mortality among people in active age as a result of trauma, chronic heart diseases, AIDS, wars, etc.

Rate of demographic ageing (Ti)

The rate of increase of the relative share of population above work age (according to the defined boundary for men and women) towards the preceding year. Calculated as a percentage.

Changes in the average population number in Bulgaria for the period 1970-2004 г.

7500000

8000000

8500000

9000000

1970 1980 1990 2000 2010

Source: World Health Organization, Regional Office for Europe. European health for all database (HFA-DB)

Population structure

Population structure according to gender Population structure according to age Analysis of the correlation of dependant contingents Population structure under, in and above work age Analysis of the relative shares of persons aged 0-14, 15-

49 and above 50 Ethnic composition, religion, maternal language Population structure according to level of education

Population gender structure

Population as of 31.12.2005

Year Total Men Women

1990 8 669 269 4 269 998 4 399 271

1995 8 384 715 4 103 368 4 281 347

2000 8 149 468 3 967 423 4 182 045

2001 7 891 095 3 841 163 4 049 932

2002 7 845 841 3 816 162 4 029 679

2003 7 801 273 3 790 840 4 010 433

2004 7 761 049 3 767 610 3 993 439

2005 7 718 750 3 743 327 3 975 423

Source: NSI,2006

Population age structure

Age classifications WHO classification

0-14 – infant age 15-44 – juvenile age 45-59 – middle age 60-74 – aged persons 75-89 – old people Above 90 – longevity

Classification for the needs of education and healthcare Under 1 – nursing age 1-3 – early infant age 4-6 – before school age 7-14 – school age

The population age structure may be characterized in four basic ways

1. Through building and analyzing of an age pyramid

2. Through correlation of dependant contingents (relation of children and persons above 65 to working population)

3. Through comparison of relative shares of persons in the three main groups 0-14, 15-49 and above 50.

4. Through relative shares of persons above 60 or above 65.

Building and analyzing an age pyramid

Възрастова пирамида на населението на България към 31.12.2005

400 000 300 000 200 000 100 000 0 100 000 200 000 300 000 400 000

0-1

1-4

5-9

10-14

15 - 19

20 - 24

25 - 29

30 - 34

35 - 39

40 - 44

45 - 49

50 - 54

55 - 59

60 - 64

65 - 69

70 - 74

75 - 79

80 - 84

85 - 89

90 - 94

95 - 99

100 +

жени брой мъже

въ

зраст

Сравнение между възрастовите пирамиди на населението на България към 31.12.2005 в градовете и селата

250 000 200 000 150 000 100 000 50 000 0 50 000 100 000 150 000 200 000 250 000

0-1

1-4

5-9

10-14

15 - 19

20 - 24

25 - 29

30 - 34

35 - 39

40 - 44

45 - 49

50 - 54

55 - 59

60 - 64

65 - 69

70 - 74

75 - 79

80 - 84

85 - 89

90 - 94

95 - 99

100 +

въ

зр

аст

мъже-град жени-град

мъже-село жени село

Analysis of the correlation of dependant contingents

Coefficient of age dependency (V) shows the number of people in „dependant" ages (population under 15 and above 65) in relation to 100 people in „independent" age (from 15 to 64). Calculated in percent.

Population structure under, in and above work age

Years Total Age groups

Under work age - % In work age - % Above work age - %

1990 100 21.6 55.5 22.9

1995 100 19.1 56.6 24.3

2000 100 16.8 58.3 24.9

2001 100 16.3 59.2 24.5

2002 100 15.9 60.1 24.0

2003 100 15.5 60.8 23.7

2004 100 15.1 61.6 23.3

2005 100 14.8 62.4 22.8

Source: NSI,2006

Coefficients of dependency 2000-2005

Source: Hr. Mitreva, NII, 2006

Populationas of 31.12.

Population aboveworkage as of

31.12.Retired -total

Insured persons

Relation ofretired toinsuredpersons

2000 г. 8 149 468 2 027 976 2 379 324 2 303 726 103.3%

2001 г. 7 891 095 1 929 683 2 370 871 2 311 091 102.6%

2002 г. 7 845 841 1 887 036 2 350 900 2 170 061 108.3%

2003 г. 7 801 273 1 845 175 2 336 806 2 393 927 97.6%

2004 г. 7 761 049 1 804 868 2 327 807 2 491 829 93.4%

2005 г. 7 718 750 1 759 875 2 313 744 2 597 061 89.1%

Population, insured persons and retired for the period 2000-2005

Analysis of the relative shares of persons in ages 0-14, 15-49 and above

50.

Progressive type – persons aged 0-14 are above 30% of the total number of population, and these above 50 are under 20%;

Stationery type – the number of persons in the two age groups 0-14 and above 50 is approximately equal and their percent relation to the total population number is respectively 25% to 25%;

Regressive type – persons in the age group 0-14 constitute under 20% of the total population number, and those above 50 – more than 30%.

Coefficient of demographic replacement

The ratio of the population numbers of incoming in the working contingent age group 15-19 and exiting from the working contingent age group 60-64.

Analysis of the relative share of persons above 60 or 65

Age structure Persons above 60 Persons above 65

Young Below 10% Below 5%

Ageing 10-15% 5-10%

Aged Above 15% Above 10%

Marriage and divorce

The marriage coefficient (b) shows the number of marriages per 1 000 people. It is calculated (per thousand) as the ratio of the number of marriages (B) throughout the year and the average population throughout the same year.

The divorce coefficient (p) shows the number of divorces per 1 000 people. It is calculated (per thousand) as the ratio of the number of divorces throughout the year and the average population throughout the same year.

MAIN DEMOGRAPHIC INDICATORS FOR 2001, 2004 and 2005

Indicator 2001 2004 2005

Total City Rural Total City Rural Total City Rural

Sex ratio (number of women per 1000 men) 1 054 1 066 1 028 1 060 1 075 1 026 1 062 1 077 1 028

Marriage (per 1000 people) 4.0 4.5 3.1 4.0 4.6 2.6 4.3 4.9 3.0

Divorce (per 1000 people) 1.3 1.6 0.6 1.9 2.2 1.2 1.9 2.2 1.2

Mean age (in years):

Population age 40.4 38.6 44.6 41.0 39.3 45.0 41.2 39.5 45.2

Age of mother at birth:

   of first child 23.8 24.4 22.0 24.5 25.2 22.4 24.8 25.6 22.5

   of child 25.1 25.6 23.9 25.8 26.4 24.3 26.2 26.8 24.4

Age at first marriage:

   Men 28.1 28.2 28.1 28.8 29.1 27.5 29.1 29.4 28.0

   Women 24.8 24.9 24.4 25.5 25.9 24.1 25.8 26.2 24.5

Age at divorce:

   Men 39.1 39.1 39.4 40.6 40.5 41.3 41.1 40.8 42.1

  Women 35.8 35.8 35.7 37.2 37.1 37.6 37.6 37.4 38.4

Ethnic composition

Source: NSI, 2005

Distribution of ethnic groups in Bulgaria as of 2001 in %

Turks 9%

Bulgarians 84%

Roma 5% Not shown

0%

Others 2%

POPULATION DISTRIBUTION ACCORDING TO RELIGION

Religion 1910 1920 1926 1934 1946 1992 2001

  Numbers

Total 4 337 513 4 846 971 5 478 741 6 077 939 7 029 349 8 487 317 7 928 901

East-orthodox 3 643 918 4 062 097 4 569 074 5 128 890 5 967 992 7 274 592 6 552 751

Islam 602 078 690 734 789 296 821 298 938 418 1 110 295 966 978

Catholic 32 150 34 072 40 347 45 704 - 53 074 43 811

Protestant 6 335 5 617 6 735 8 371 - 21 878 42 308

Judaism 40 067 43 232 46 431 48 398 43 335 2 580 653

Armenian-gregorian 12 259 10 848 25 402 23 476 - 9 672 6 500

Others and not shown 706 371 1 456 1 802 79 604 15 226 7 784

Undefined - - - - - - 308 116

Source: NSI, 2005

Source: NSI, 2005

Population distribution according to religionas of 2001 in %

Catholic 0,55

Muslim 12,20

Protestant 0,53

Other 0,19

Not defined

3,57 Not shown0,31

East-orthodox

82,64

Population distribution according to education

Source: NSI, 2005

Population distribution according to education in %

Higher 24%

No education0%

Primary 20%

Secondary 56%

Demographic indicators for population dynamics

Dynamic demographic

indicators

Mechanical movement of

population

Natural population movement

(vital processes)

External migration

Internal migration

Immigration

Emigration

Urbanization

Cyclic movement

Birthrate

Mortality

Natural growth

Integral indicators

AALEAge adjusted life expectancy

HALEHealth adjusted life expectancy

DFLEDisability free

life expectancy

QALYQuality adjusted

life years

DALYDisability adjusted

life years

Indicators for mechanical movement of population

External migration Internal migration Cyclic movement

Indicators for natural movement of population

Main concepts “Childbirth" means is the process at the end of a human

pregnancy that results in a baby being born A live birth occurs when a fetus, whatever its gestational

age, exits the maternal body and subsequently shows any signs of life

Stillbirth is considered the delivery of child that by the termination of pregnancy didn’t show any signs of life and the pregnancy has lasted no less than 28 weeks

Abortion is considered the delivery of child that by the termination of pregnancy didn’t show any signs of life and the pregnancy has lasted less than 28 weeks

Birth rate

Children born alive through the year х 1000

Birth rate =Average yearly number of population

Birth rate is assessed using a three-stage scale: low – below 15%, medium – 15-25% high – above 25%.

General fertility rate Children born alive х 1000

Fertility =Average yearly number of women aged 15 - 49

Birthrate and general fertility rate (1990 - 2005)

 1.319.22005

 1.299.02004

 1.238.62003

 1.218.52002

 1.248.62001

 1.279.02000

 1.238.61995

 1.8112.11990

General fertility rate3Birthrate (per 1000)

Year

Source: NSI, 2006

Age-specific fertility rate

Represents the number of live births per 1000 women of a specified age in one year.

Age-specific fertility rate in Bulgaria for 1980-2000

Source: NSI, 2006

Age-specific fertility rate

0102030405060708090

100110120130140150160170180190200210

Age

Co

effi

cien

t

1980 80,3 192,8 92,8 32,2 9,7 2,1 0,1

1990 68,3 159,4 78,3 28,8 9,4 1,8 0,1

1995 53,5 100,6 61,8 22,4 7,5 1,5 0,1

1997 45,1 85,2 56,9 22,4 7,3 1,6 0,1

2000 45,5 89,7 72,9 32,3 9,5 1,9 0,1

15-19 20-24 25-29 30-34 35-39 40-44 45-49

Specific indicators for assessment of population reproduction

Total fertility rate – represents the average number of children, that a woman would give birth to, through her entire fertile period, if the age-specific fertility rate remains the same as at the present moment for which it is calculated;

Gross fertility rate of population is a complex indicator, representing the average number of girls born of a mother in her fertile age;

Net fertility rate of population is the average number of girls born of a mother in her fertile age (15-49), which will live up to the age their mother had by the moment of their birth.

An example of calculating total fertility rate and gross fertility rate

We use the data for age-specific fertility rate for each year. The coefficients for each age group are multiplied by 5 (column 3 of the table), which will give us information ho many live births would produce 1000 women for the 5-year interval. The products of column 3 are summed (the sum is 1259,6) – this is the number of live births per 1000 women for the next 5-year interval after 2000.

Age Year 2000

Multiplied by 5

1 2 3

15-19 45,5 227,5

20-24 89,7 448,5

25-29 72,9 364,5

30-34 32,3 161,5

35-39 9,5 47,5

40-44 1,9 9,5

45-49 0,1 0,5

An example of calculating total fertility rate (continuation)

Finally, we divide this sum by 1000 and get the total fertility rate, which is 1,26, meaning that if no changes occur in age-specific fertility rate, a woman from the offspring of 15-year old, which by 2000 have reached reproductive age, will have an average of 1.26 children by their 49 anniversary. If we keep in mind that a family couple reproduces if it has at least to children, it becomes clear that by the year 2000 Bulgaria is in the stage of narrowed reproduction.

The sum of column (3) is 1259,6.1259,6 : 1000 = 1,26.

Total fertility rate = 1,26.

The gross rate is calculated by multiplying the total fertility rate by

the relative share of girls in the structure of live born for the year. For

2000 the relative share of girls is 0,488. Consequently, the gross rate

for the year 2000 is:Gross fertility rate = 1,26 х 0,488 =

0,61.

Stillbirth and abortion rate

Number of stillbirths х 1000

Stillbirth rate =Number born (alive and stillbirths)

Number of abortions for a given territory in a given period х 1000

Abortions rate =Number of women (15-49) on the same territory for the same period

0

50000

100000

150000

200000

1970 1975 1980 1985 1990 1995 2000 2004

Total number of abortions in all ages

Source: World Health Organization, Regional Office for Europe .European health for all database (HFA-DB)

Reasons for death

„All those ailments, pathological states or trauma that have lead to the occurrence of death or have facilitated death, as well as circumstances that have lead to incidents or acts of violence causing such trauma”

Primary cause of death

Primary cause of death can be defined as :

„а) illness or trauma causing a number of pathological processes directly leading to death or

б) circumstances that have lead to an incident or act of violence causing mortal trauma.”

International form of medical certificate for cause of death

Death reason

Approximate time interval between onset of

pathological process and death

І. Disease or state that have directly lead to death *

а) …………………………..caused (or attributed to) …………………………..

…………………………..

……………………………

…………………………….

Preceding causesPathological states, if any, that have

lead to the emergence of the above stated cause;

The leading cause of death is shown last

b) …………………………..caused (or attributed to)c)……………………………caused (or attributed to)d)……………………………

ІІ. Other important states contributing to death, unrelated to the illness or the pathological state

.....………………………….……………………………….

* Symptoms and signs accompanying death (mechanism of death) like heart failure, breathing disorders, are not included here. Only ailments, trauma and complications that have lead to death are included.

An example of defining the cause of death

The medical certificate of death, comprising four events in a chain leading directly to death, should be filled in the following way [1] :

а) Pulmonary artery embolism

б) Pathological fracture

в) Secondary femoral cancer

г) Mammal cancer

[1] Example from ICD-X, tome ІІ.

Mortality Groups of indicators

Not standardized – intensive indicators, measuring the frequency of a health event in a given year and territory.

Standardized – when comparing gross coefficients or specific indicators by reasons (calculated for the entire population), but under existing differences in age structure of the population in compared populations.

Standardization aims to eliminate the differences in these factors and show what would be the health event if the compared populations would have identical age structure.

Specific coefficients – measuring the frequency of health events in different subgroups of population or by different causes.

Proportions – structural or extensive indicators showing the distribution of causes of death

Not standardized indicators of mortality

Number of deceased х 1000

Total mortality =Yearly average number of population

When assessing total mortality a scale of three stages may be used :

low – below 10 ‰, medium – 10-15 ‰ high – above 15 ‰.

Total mortality in ‰ in Bulgaria (1965-2005) with calculated trend

y = 0,528x + 8,7962

0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0

16,0

18,0

Source: NSI, 2006

Standardized mortality indicators

1000

1100

1200

1300

1400

1500

1980 1985 1990 1995 2000 2005 2010

Fig. 10. Standardized mortality coefficient in Bulgaria per 100000

Source: World Health Organization, Regional Office for Europe .European health for all database (HFA-DB)

Standardization of frequencies

The standardization of frequencies is a set of techniques used for eliminating, as far as possible, the influence of different age and sex distributions when comparing the mortality or morbidity of population of one or more countries. For the purpose of comparing frequencies from different groups, a standard population with known age and gender structure is used.Standardization may be fulfilled through direct or indirect method.Direct method of standardizationThis method is applied when the age-specific indicators of the compared groups are known. These indicators are applied to the standard population for calculating the expected number of cases (deceased, diseased) in each age group in case their age distribution is the same as in the standard population. Obtained numbers are summed and divided by the total number of standard population.

Indirect method of standardizationThis method is used when the age-specific frequencies for mortality in a given population are missing or the numbers in some age groups are too small. The expected number of cases calculated in this way is compared to the actually observed number of cases from a certain health event. The ratio observed/anticipated is multiplied by 100 in order to obtain standardized ratio, which shows comparisons without biasing factors such as different age structure.

Example. Mortality from disease х in youngsters from region у.

Total number observed 3850. Total number of deceased with illness х (in corresponding age-specific mortality among entire population) 32О. Anticipated deaths 0,14. Standardized mortality 32/0,14=228,6

Standardizedmortality

rate (SMR)

Number of cases observed

Number of cases anticipated

=х

100

Example Mortality from disease х in youngsters in

region у

Total number of observed 3850

Cases of death from disease х (in corresponding age-specific mortality among entire population)

32

Expected deaths 0,14

Standardized mortality 32/0,14=228,6

Specific indicators of mortality

Mortality according to habitation Mortality according to gender Mortality according to age Mortality by causes

Mortality according to residence

0,0

5,0

10,0

15,0

20,0

25,0

1965 1970 1975 1980 1985 1990 1995 2000

Urban Rural

Bulgarian population mortality according to residence (1965-2000)

Source: NSI, 2006

Mortality according to gender

0,0

5,0

10,0

15,0

1970 1980 1990 2000

Gender - standardized mortality in Bulgaria

(1970-2000)

Total Men Women

Source: NSI, 2006

Maternal mortality

Maternal mortality reflects the frequency of death in pregnant women up to the 42 day after pregnancy termination, regardless of its duration, complications during pregnancy or the course of delivery.

Number of pregnant or lying-in women dead х 1000 000Maternal mortality =

Number of children born alive

Leading causes of maternal mortality

Direct obstetrics reasons – deaths as a result of complications of pregnancy, delivery or post-delivery period; omissions; incorrect treatment or a chain of events following some of the mentioned above factors;

Extra-genital reasons – deaths as a result of preceding disease or condition, manifested during pregnancy, which is not due to direct obstetrics cause but is aggravated by physiologic consequences of pregnancy.

Infant mortality

Groups of indicators: Uncorrected (simple) coefficient – calculated as the number of deceased children

for a given period on a certain territory to the number of children born alive for the same period and same territory

Corrected coefficient – it is used when the birthrate in two consecutive years differs considerably and because part of the deceased children from the age group 0-1 were born in the previous year, the number of born alive in this year should also be taken into account. The classic way of correction is to use 2/3 of the born alive in the current year plus 1/3 of the born alive from the preceding year in the denominator. Other authors suggest that the coefficient should be corrected by 4/5 of the born alive through the present year and 1/5 from the previous one.

Age-specific indicators – reflecting mortality through the sub-periods of infant’s life from 1 year on.

Specific indicators – measure the frequency of dying among children from concrete anomalies or diseases

Others – according to residence, gender, maturity and other criteria

Uncorrected (simple) coefficient

Common coefficient of infant mortality

Infant mortality

Number of newborns dying under 1 year of age

Number of live births during the year= х 1000

Comparative analyses are based on a five-stage scale

• very low – below 10 ‰;• low – 10-14 ‰;• average – 15-24 ‰;• high – 25-49 ‰;• very high – над 50‰.

Periods in infancy before 1 year of age

Perinatal – (from lat. peri – around and natus – delivery) – from 22 week of gestation (154 of the intrauterine development – weight approximately 500 g) up to the 7th day after delivery

Neonatal – this period starts with the delivery and ends to the 28th day after delivery. This period is subdivided to:

– Early neonatal – from 0 to 6 days from delivery– Late neonatal – from the 7th day to the 28th day from

delivery Post-neonatal - from day 29 after delivery to 1 year

Age-specific indicators of infant mortality

Perinatal infant mortality

Stillbirths + born alive, dying in the first 6 days after delivery

Newborns (dead- and alive)

= х 1000

Neonatal infant mortality

Infant deaths from 0 to 28 days

Born alive= х 1000

Early neonatal infant mortality

Infant deaths from 0 to 6 days

Born alive= х 1000

Late neonatal infant mortality

Infant deaths from 7 to 27 days

Born alive minus born dead up to day 6 = х 1000

Post-neonatal infant mortality

Infant deaths from day 28 to year 1

Born alive minus deceased until day 27

= х 1000

Other coefficients and indicators

Coefficient of intrauterine mortality Coefficient of stillbirth rate Coefficient of stillbirth rate accounting for weight Coefficient of early neonatal mortality accounting for

weight Coefficient of perinatal mortality accounting for

weight Coefficient of neonatal mortality accounting for

weight

Natural growth

Natural growth

Number of born alive minus deceased

Yearly average number of population

= х 1000