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A zone design approach A zone design approach for investigating inequalities for investigating inequalities
in infant mortalityin infant mortality
Konstantinos Daras (University of East Anglia)
Seraphim Alvanides (University of Newcastle)
Ian Gregory (Queen's University Belfast)
3rd International Population Geographies Conference
19 -21 June 2006, Liverpool, UK
2
The Geography of Infant Mortality The Geography of Infant Mortality in England & Wales (1911-1971)in England & Wales (1911-1971)
Was there a north-south divide?
Looking at inequalities: Between urban/rural LGDs Between/within counties Between/within automated zones
3
Infant Mortality Rate (IMR)Infant Mortality Rate (IMR)
Infant mortality: Deaths before 1st birthday per 1,000 live births
•Social class •Urban/rural
•Low income•Overcrowded•Unhygienic
Infant mortality is related to:
4
Infant Mortality Rates Infant Mortality Rates in England and Wales (1840-1970) in England and Wales (1840-1970)
Wo
rld
Wa
r I
Wo
rld
Wa
r II
(Source: Beaver (1973): p. 244)
5
Decline of Infant Mortality Decline of Infant Mortality
Conventional explanations: Cities had high rates because of rapid urban growth Lower rates were driven by improvements in
sanitary conditions in towns and by better health care.
Improvements started simultaneously across the whole country in the 1880s.
After Woods et al (1988 & ’89); Lee (1991); Williams and Galley (1995); Woods (1997)
6
Data sources (1)Data sources (1)
The Great Britain Historical GIS (Gregory and Southall, 1998)
1911: 2061 Local Gov. Districts 1928: 2037 Local Gov. Districts 1951: 1527 Local Gov. Districts 1971: 1419 Local Gov. Districts
(Data aggregated to 1971 level)
Infant deaths (before 1st birthday)
Infant births Estimated population Urban/rural classification
7
Data sources (2)Data sources (2)
Wo
rld
Wa
r I
Wo
rld
Wa
r II
(Sou
rce:
Bea
ver
(197
3):
p. 2
44)
1881
1928
1931
1911
1951
1971
Available datasets
Phases of inequality change according Lee (1991)
8
Measuring InequalitiesMeasuring Inequalities
Gini coefficient Coefficient of variation Variance of logarithms Theil’s entropy index
•Between areas inequalities: Gini coefficient of areas•Within areas inequalities:
N
Ga Ga: Gini coefficient of area aN : number of areas
9
Zone DesignZone Design
Aggregation of areal units into zones, so that certain criteria are satisfied.
Available zone design systems AZP (no GIS): Openshaw (1977, 1984) ZDES: Alvanides et al. (1999, 2000) AZM: Martin (2002) A2Z: Daras (2005), O-O & Graph theory
10
How A2Z worksHow A2Z works
ZONE 1ZONE 2
AREAL UNIT
NEW ZONE 2
NEW ZONE 1
OB
JEC
TIV
E F
UN
CT
ION C
ON
TIG
UIT
Y C
HE
CK
• Optimises an objective functionOptimises an objective function• Controls the contiguity of zoneControls the contiguity of zone
11
A2Z componentsA2Z components
Initial AggregationInitial Aggregation ( (Random or userRandom or user))
Shape ConstraintsShape Constraints (Weak or Strong compactness(Weak or Strong compactness))
Boundary ConstraintsBoundary Constraints ( (Railway, A road, WardsRailway, A road, Wards))
Objective FunctionObjective Function ( (HomogeneityHomogeneity))
12
Zone design settingsZone design settings
62 output zones
Random initial aggregation
Weak shape constraint
Dataset <year>
Objective FunctionSimilarity
Infant MortalityZO
NE
DE
SIG
N
Output Zone M<year>
Dataset <year>
Objective Function Similarity
PopulationZO
NE
DE
SIG
N
Output Zone P<year>
Target IM patterns Target Urban/Rural zones
Infant Mortality RatesInfant Mortality Rates((LGD levelLGD level))
LRDs (1928)0 - 3333 - 6464 - 112112 - 333
LGDs (1928) LRDs (1951)0 - 1818 - 3434 - 5656 - 136
LGDs (1951) LRDs (1971)0 - 88 - 1818 - 3131 - 77
LGDs (1971)
LRDs (1911)0 - 7373 - 116116 - 165165 - 353
LGDs (1911)
14
Between LGDs inequalitiesBetween LGDs inequalities
0.19
0.2
0.21
0.22
0.23
0.24
0.25
0.26
0.27
1911 1928 1951 1971
Year
Gin
i co
effi
cien
t
All
Urban
Rural
1911 Counties58 - 9393 - 111111 - 130130 - 154
1928 Counties38 - 4848 - 5858 - 6868 - 92
1951 Counties18 - 2626 - 2929 - 3434 - 55
1971 Counties7 - 1515 - 1717 - 1919 - 26
Infant Mortality RatesInfant Mortality Rates((County levelCounty level))
Output zones (1911)62 - 9595 - 114114 - 146146 - 174
Output zones (1928)0 - 3333 - 5656 - 7575 - 92
Output zones (1951)14 - 2525 - 3131 - 4040 - 51
Output zones (1971)6 - 1010 - 1616 - 2020 - 29
Infant Mortality RatesInfant Mortality Rates((output zones based on output zones based on the similarity of IMRthe similarity of IMR))
Output Zones (1911)77 - 9999 - 123123 - 143143 - 168
Output Zones (1928)77 - 5656 - 6868 - 87
Output Zones (1951)18 - 2424 - 2929 - 3535 - 45
Output Zones (1971)0 - 77 - 1616 - 2020 - 28
Infant Mortality RatesInfant Mortality Rates((output zones based on output zones based on
the similarity of populationthe similarity of population))
18
Between areas inequalityBetween areas inequality
0.06
0.08
0.1
0.12
0.14
0.16
0.18
1911 1928 1951 1971
Year
Gin
i co
effi
cien
t
County
Inf. Zone
Pop. Zone
19
Within areas inequalityWithin areas inequality
0.15
0.16
0.17
0.18
0.19
0.2
0.21
0.22
0.23
1911 1928 1951 1971
Year
Gin
i co
effi
cien
t
County
Inf. Zone
Pop. Zone
20
Summary (1)Summary (1)
There has been a steady decline in infant mortality since the 1900s
This masks some complex geographical variations: Between urban area inequalities remained fairly constant
in 1928 and 1951 Between rural area inequalities increased throughout the
study period The automated zones suggest a decline of inequalities in
1951, while the counties record such reduction in 1971 Possible explanation: at period 1928 -1951 urban
inequalities remain steady because of better health care.
21
Summary (2)Summary (2)
Traditional descriptions and explanations of these are limited and over-simplified
This method allows comprehensive description but does not provide explanation
Zone design can provide a useful tool for highlighting problems.
22
Further researchFurther research
North/South divide: 1911- 2001 Automated zones (2 zones)
Further investigation of 1928 – 1951 period- - - - -
Different aggregation levels (scale) Extend the analysis of IM inequalities
on annually data 1911-2001 Any available socio-economic data
(possible explanations).
A zone design approach A zone design approach for investigating inequalities for investigating inequalities
in infant mortalityin infant mortality
Konstantinos Daras ([email protected])
Seraphim Alvanides ([email protected])
Ian Gregory ([email protected])
3rd International Population Geographies Conference
19 -21 June 2006, Liverpool, UK