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GRIDS AS USEFUL TOOLFOR REBUILDING TIME SERIES

Claude GRASLAND (Univ. Paris Diderot)

Nicolas LAMBERT (CNRS-RIATE)

Hélène MATHIAN (CNRS- Géographie-cités)

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SPECIFIC PROBLEM

HOW IS IT POSSIBLE TO ANALYZE EVOLUTIONSWHEN TERRITORIAL DIVISIONS ARE CHANGING ?

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GEOM2

GEOM1

GEOM1 x GEOM2

GENERAL PROBLEM

HOW IS IT POSSIBLE TO COMBINE DATA AVAILABLEON TWO DIFFERENT GEOMETRIES ?

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SOLUTION n°1 : TRANSFER DATA BY GRID

GEOM1xV1

SOLUTION

Auxilliaryattribute

GRID

V1_GRID

GEOM2xV2

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GEOM2xV2

GEOM1xV1

SOLUTION n°2 : GRIDDING + SMOOTHING

AncillaryvariableGRID

V1_GRID

V2_GRID POT_V2

POT_V1

POT_V2 / POT_V1

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GRIDDING + SMOOTHING

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TEST AREA : South-Western France

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OBJECTIVE : Annual growth rate of population 1990-2006

GEOM252 Zones d’emploi

GEOM155 Arrondissements

???

???

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NUTS2 NameAggregatedpopulation

1990

Aggregatedpopulation

2006

Annual populationgrowth 1990-2006 (%)

FR61 Aquitaine 2795830 3119757 0,69

FR62 Midi-Pyrénées 2430663 2776821 0,84

FR81 Languedoc-Roussillon 2114985 2534155 1,14

AN EXACT BUT NOT INTERESTING SOLUTION : Aggregation at first common level

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Grid of population1km x 1kmFrom EEA

ANCILLARYVARIABLE

100 000 Grid points

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POP06 / ZEMP

POP90 / ARRD

ESTIMATION OF TARGET INDICATOR

POP00/GRID

POP90 /GRID

POP06/ GRID POT (POP06)Gauss 20 km

POT (POP90)Gauss 20 km

ANNUAL GROWTHRATE 1990-2006Gauss 20 km

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POP06 / ZEMP

POP06 / ARRD

ESTIMATION OF RESIDUAL « NOISE »

POP00/GRID

POP06/GRID*

POP06/GRID POT (POP06)Gauss 20 km

POT (POP06)*Gauss 20 km

POT(POP06) *____________

POT (POPO6)

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Smooth 10 km

0 +1%-1%-5%0.25 0.5 0.75 1.0 +5%(%)

Increase of population 1990 - 2006 Noise introduced by the method

GOOD SPATIAL RESOLUTION … … BUT HIGH LEVEL OF NOISE

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Smooth 40 km

0 0.25 0.5 0.75 1.0 (%)

Increase of population 1990 - 2006

+1%-1%-5% +5%

Noise introduced by the method

LOW SPATIAL RESOLUTION … … BUT LOW LEVEL OF NOISE

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Smooth 20 km

0 0.25 0.5 0.75 1.0 (%)

Increase of population 1990 - 2006

+1%-1%-5% +5%

Noise introduced by the method

GOOD COMPROMISE BETWEEN SPATIAL RESOLUTION AND NOISE

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SYNTHESIS : Signal & Noise

Mean Noise < 1%

Max Noise < 5%

Gaussian Smooth > 22 km

Gaussian Smooth > 22 km

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CONCLUSION & PERSPECTIVESSmooth + Grid

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Longer Time Series

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Multilevel spatial analysis

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Cross Border Analysis

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Modifiable Area Unit Progress

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Thank you for your attention !

Grasland, Mathian, Vincent, 2000,Statistical Journal of UN-ECE

Grasland, Madelin, 2007,ESPON 3.4.3, MAUP