methodological issues of population projections in small states the case of cape verde joint...

Methodological issues of population projections in small States

the case of Cape Verde

Joint Eurostat-UNECE Work Session on Demographic ProjectionsINE - Lisboa (Portugal) , 28-30 April 2010

BRITO, [email protected]

RODRIGUES, [email protected]

Methodological issues of population projections in small States. The case of Cape Verde

Brito, Pedro: Rodrigues, Teresa


Main Issue:

To discuss possible alternative methods of performing population projections in small political independent States

(To consider Cape Verde and its 10 islands

as a case study)

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Republic of Cape Verde




Methodological assumptions

To project Cape Verde’s population evolution for 2000-2025, based on different methods;

To present some hypothetical demographic “scenarios”, both for total and insular population

To make a critical analysis of the results obtained

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Our Goal

To make some aggregation tests of the 10 existing islands, according to their convergence or divergence behavior patterns (both natural and/or migratoryboth natural and/or migratory).

To verify the probable existence of future different internal (insular) trends / “local histories”

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Starting points

Cape Verde is no exception to this ruleCape Verde is no exception to this rule

a. an insular Country, located in the Atlantic Ocean in the West African coast

b. composed by 10 islands and several islets and divided in 22 municipalities

c. a micro-island State with less than half a million inhabitants (Census 2000: 431989)

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Data analysis becomes increasingly complex as the size of the projected population decreases



Starting points

d. Annual Average Increase Rate (1991-2000): 2.39%

e. extremely young population structure (42% under 15 years; 54% under 20 years)

f. Crude Birth Rate=29.5 ‰; Crude Mortality Rate=6.4 ‰; Infant Mortality Rate=33.3‰; General Fertility Rate=123.3 ‰; Synthetic Fertility Index=4.0 children/woman; Average Life Expectancy at Birth (M/F)=71 years; Mean Procreation Age=29 years

g. Huge internal diversity in natural and migratory behaviours

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Methodologies

For this exercise we rely on the method of components (Cohort Cohort SurvivalSurvival) to present some hypothetical “scenarios”, based on the Census of 2000 and all demographic behaviors and its trend in the 1990s;

In subsidiary terms we used mathematical methodsmathematical methods and ratioratio. The first one considers the average annual growth rate recorded in the 90’s to project population volume by 2025; the second estimates the same population based on the weight it had both in 1990 and 2000, compared to the population of ECOWAS.

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Prospective Hypothesis: future demographic dynamics

Estimation Criteria on Mortality, Fertility and Migration Trends (2000-2025)

2000 - 2005 2005 - 2010 2010 - 2015 2015 - 2020 2020 - 2025IMR= 28,05 IMR= 25,1 IMR= 22,7 IMR= 20,5 IMR=18,7

ALE0 (M)= 67,2; ALE0( F)=75,4

ALE0 (M)= 68,4; ALE0 (F)=76,2

ALE0 (M)= 69,4; ALE0 ( F)= 77

ALE0 (M)= 70,3; ALE0( F)= 77,7

ALE0 (M)= 71,1; ALE0( F)= 78,2

Birth (estimates)= 63888





Birth (M)= 31177; Birth (F)= 32711)

Birth (M)= 30399; Birth (F)= 28974

Birth (M)= 26510; Birth (F)= 25267

Birth (M)= 21356; Birth (F)= 20355

Birth (M)= 18286; Birth (F)= 17429

Migr. Balance= - 4320/5 Constant Constant Constant ConstantAMIR= -0,2

AAIR= 2,2 AAIR= 1,9 AAIR= 1,5 AAIR= 1,0 AAIR= 0,8




National Results (1)

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National Results, with and without migratory effect

1990 2000 2005 2010 2015 2020 2025

Scenari

o 1Scenari

o 2Scenari

o 1Scenari

o 2Scenari

o 1Scenari

o 2Scenari

o 1Scenari

o 2Scenari

o 1Scenari

o 2Total Population 341491 43189 482479 478159 529310 524959 576863 565843 600239 595840 625344 625245 Male 161495 207994 235538 233378 262096 258924 283474 281294 300334 298146 314452 312456Female 179996 223995 246941 244781 267214 266035 293389 284549 299905 297694 310892 312789

General Fecundity Rate 185,43 123,3 99 99 75 75 61 61 40 40 40 40Synthetic Fertility Index 6,32 4 2,9 2,82 2,87 2,78 2,83 2,74 2,8 2,7 2,5 2,3Infant Mortality Rate 65 29,8 26,3 26,3 23,9 23,9 21,4 21,4 19,6 19,6 17,8 17,8Active Renovation rate - 27,2% 22,8% 21,1% 19,9% 20,2% 13,2% 13,4% 12,2% 12,4% 8,7% 9,6%

Average Life Expectancy at Birth (MF) 68,5 70,8 72 72 72,9 72,9 73,8 73,8 74,4 74,4 74,7 74,7Average Life Expectancy at Birth (M) 65,7 66,5 67,9 67,9 68,9 68,9 69,9 69,9 70,7 70,7 71,1 71,1Average Life Expectancy at Birth (F) 71,3 74,9 75,8 75,8 76,6 76,6 77,4 77,4 77,9 77,9 78,2 78,2Scenario 1 – Natural TrendScenario 2 - Repulsion



Cape Verde Population Structure – Natural Trend (2000 and 2025)


Graphic 2: Cape Verde 2025 (Natural Trend)

0 1 2 3 4 5 6 7 8 9

2000

1990

1980

1970

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F

Birth’s year

0123456789

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M

Birth’s year

+95908580757065605550454035302520151050

Graphic 1: Cape Verde 2000 (Natural Trend)

0 1 2 3 4 5 6 7 8 9

2000

1990

1980

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FBirth’s year

0123456789

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MBirth’s year

+95908580757065605550454035302520151050

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Cape Verde Population Structure – Alternative Trend (2000 and 2025)


Graphic 4: Cape Verde 2025 (Alternative Trend)

0 1 2 3 4 5 6 7 8 9

2015

2005

1995

1985

1975

1965

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1945

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1925

1915

FBirth’s year

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MBirth’s year

+95908580757065605550454035302520151050

Graphic 3: Cape Verde 2000 (Alternative Trend)

0 1 2 3 4 5 6 7 8 9

1990

1980

1970

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1890

FBirth’s year

0123456789

1990

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MBirth’s year

+95908580757065605550454035302520151050

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Results (2000-2025)

Without Migrações With MigraçõesDemographic Growth in the next 25 years

Demographic Growth in the next 25 years

Actives and aging increasing Trend for aging of the population

Decreasing of AAIR Mortality Decreasing

Mortality and Natality decreasing Migratory balance each less negative time

Resultado Final (2000-2025)

Population will tend to aging

Decline of almost all the demographic indices

Increase of the indices of aging, longevity and dependence of the aged

Average Life Expectancy at birth increasing

Infant Mortality Rate decreasing




Main Conclusions

Micro-demographic variables, such as birth / fertility, mortality and migration rates are the most important factors for population growth in Cape Verde;

Mortality continues to decline at all age groups and islands, as a result of improvements in sanitation and socio-economic;

Life expectancy at birth increased significantly between 1990 and 2000;

Cape Verdean population will continue to grow in the near future, at least until 2025, no mater the chosen scenario.

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Regional Results (2)

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Population estimates for Cape Verde’s islands (2000-2025)

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Demographic Projection 2000 -2025 by Islands (Alternative Scenario)

IslandsYears

2000 2005 2010 2015 2020 2025Santo Antão 46865 51873 56951 61386 64640 67830

São Vicente 66764 73900 81133 87451 92087 96632

São Nicolau 13583 15035 16506 17792 18735 19660

Sal 14727 16301 17897 19291 20313 21316

Boavista 4178 4625 5077 5473 5763 6047

Maio 6713 7497 8225 8964 9327 9718

Santiago 235196 260333 285813 308072 324404 340414

Fogo 37201 41177 45207 48728 51311 53843

Brava 6762 7485 8218 8858 9327 9788

Total 429454 475353 521879 562523 592344 621576



Population estimates for Cape Verde’s islands (2000-2025)

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Demographic Projection 2000 -2025 by Islands (Alternative Scenario)

IslandsAnos

2000 2005 2010 2015 2020 2025Santo Antão 46865 51873 56951 61386 64640 67830

São Vicente 66764 73900 81133 87451 92087 96632

São Nicolau 13583 15035 16506 17792 18735 19660

Sal 14727 16301 17897 19291 20313 21316

Boavista 4178 4625 5077 5473 5763 6047

Maio 6713 7430 8158 8793 9259 9716

Santiago 235196 260333 285813 308072 324404 340414

Fogo 37201 41177 45207 48728 51311 53843

Brava 6762 7485 8218 8858 9327 9788

Total 440003 487030 534698 576341 606894 636845



From the demographic point of view there are 3 groups of Islands:

1- Islands with a fast growth

•Santiago ; São Vicente and Sal (Development Concentration Poles; moderate Fecundity + high migratory balance)

2- Islands with a moderate growth

•Fogo and Santo Antão (Sources of internal and international migrations; high Fecundity rates + negative migratory balance);

3- Islands with a slow growth

•Boavista; Maio; São Nicolau and Brava (Sources internal and international migrations ; small fecundity + very negative migratory balance)

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4. Islands with very reduced population and a very high probability error:

Brava - 6762 inhabitants

Boavista - 4178 inhabitants

Maio – 6713 - inhabitants

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Main Conclusions

The more economic and social developed islands remain the major demographic poles of attraction (Santiago; Santa Catarina; São Vicente; Sal and Boavista in some ways);

Islands with higher fecundity rates are not the ones where growth rates are highest ;

Migrations (internal and international ones) represent the major importance to explain diferentials on populational dynamics;

Demographic projections at level of the municipalities are impossible or present major errors, as there are municipalities with vey small volumes of residents.

…

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Thank You.

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