Ireland from Boundary Geography to Geo referenced Dwellings in Census 2011Not a pointless process

Joint UNECE/Eurostat Meetings on Population and Housing Censuses

Friday 2 October 2015Gerry Walker

Central Statistics Office, IrelandGerry.Walker@cso.ie

• Conduct of Irish Census• Boundary and Code approach in

2006• Use of GIS in 2011• New outputs for Census 2011• Cost of GIS and mapping• Savings using GIS

Presentation Outline

• Sunday, 10 April 2011• Traditional Delivery and Collection• 4,866 Enumerators, 490 Supervisors• Enumerators paid on piece work• Postal Address Register + Full Visual

Enumeration• 5 Week Delivery, 5 Week Collection• Data on Housing stock, Households, Present

and absent persons • Response near complete - proxy forms for

14,000 persons 0.3%• Preliminary count 81 days after Census day• Total Cost €53M

Conduct of Census 2011

• Designation was manual operation• GeoDirectory – address point counts • Drawing boundaries on draft paper maps by

hand• OSI digitised hand drawn boundaries• OSI printed paper maps• Very labour intensive• One desktop ARCGIS licence

Designation=Breaking the country into manageable work loads taking account of difficulty to survey ensuring full geographic coverage

Census Geography in 2006

Geography Coding

• Enumerators maps with red dots for GeoDirectory buildings

• Blank enumerator record book

• Full visual enumeration

• Geography coded on form by enumerator – County, Enumeration Area, ED, Street/Town land code and sequential 3 digit ID assigned by Enumerator

Geography Coding in 2006, 2002....

2006 Enumerator Map

2006 Geography

• Prone to Error Misreading boundary off map

Boundary code transcription errors

Back coding highlighted errors 244 out of 3452 ED(LAU 2) average 1.1% error

45% Enumerator error, 31% OCR false positives, remainder were boundary errors on maps and points on boundaries.

• Very labour intensive

• No link back to X,Y or the previous Census

• New geography required manual recoding for split ED/Townlands

Short comings

GIS use in Census 2011

Optimise the placement of field staff

Setting field travel cost caps

Use of GIS in 2011

• Enumeration Areas built on Atomic Small Areas

• Enumerators maps with red dots for GeoDirectory address points with 4 digit ID number within EA (D.No).

• Multi address buildings distinguished

• Output to PDF, QC and print

Designation and mapping

2011 Map

Use of GIS in 2011

• Pre-Addressed enumerator record book

• Still do a full visual enumeration

• Geography coded on form by enumerator – County, Enumeration Area, Small Area.

• Can now link back to GeoDirectory X,Y via D.No

Geography 2011

• 49K (2.5%) new dwellings not on GeoDirectory digitised from position marked by Enumerator

Use of GIS in 2011

• Scan/capture/code/cleanse forms and reconcile with ERB to come up with definitive list of Dwelling Nos.

• Export 49,000 new dwellings to centroid of small area and move to position marked by enumerator on their map.

• Move 1,800 dwellings with location errors• Identify clusters of new housing and urban

expansion expand boundariesCreate new census towns.

• Cookie cutter boundaries to code points to ANY geography with an electronic boundary. Boundary slivers, coastal high water mark issues Islands, Labelling and attribution errors

Census Geography Processing

New Outputs for Census 2011

• Have X,Y for each dwelling and household

• Allowing flexible geography subject to boundary availability and disclosure constraints

• Publish Area Population Statistics for 18,848 Atomic Small Area level (50-150 Households) around end of June 2012

• Release place of work and school micro data file to bone fide researchers signing confidentiality contract .

New Outputs

New Outputs for Census 2011

• 2006 publications had 7 maps• 2011 publications had 95 maps• 2011 dot maps• SAPMAP now at small area• http://census.cso.ie/sapmap/ • 1 KM grid data set Sex X 3 Age

groups – 16.5% cells suppressed.

• Partnership with AIRO• 4 Census mapping tools

 

AIRO/CSO PDR 2011 National Mapping Viewer

Persons per Km2No inhabitants

< 10

10 < 25

25 < 50

50 < 100

> 100

1 Km²Grid cells

Small Areas Census 2011

Population density

Flexible Geographical Outputs – Co Galway

New Outputs for Census 2011

New outputs for Census 2011

• Electoral Division, Small Areas• De facto count of males, females and total

population• No of Permanent private housing units• The total unoccupied dwellings on Census• Total vacant• Total housing stock• Vacancy rate %

• Towns Legal and Census Towns• Constituencies, Local Electoral Areas• Garda Administrative Areas

Generalised Boundary SHP Files with Census counts

COUNTY COUNTYNAME SAPSED SAPSEDNAME SAPSSA Male2011 Female2011 Total2011 PPOcc2011 Unocc201105 D·n Laoghaire-Rathdown05037 037 Dundrum-Balally 267078011/01 151 125 276 137 2227 Galway County 27107 107 Cloonkeen 067066002 125 106 231 78 1801 Carlow County 01041 041 Ridge 017043001 131 142 273 86 1001 Carlow County 01037 037 Oldleighlin 017037002 121 112 233 80 1101 Carlow County 01037 037 Oldleighlin 017037001 166 170 336 99 1701 Carlow County 01032 032 Leighlinbridge 017031001 150 155 305 102 1301 Carlow County 01020 020 Clogrenan 017012001 183 156 339 112 1201 Carlow County 01020 020 Clogrenan 017012002/017012003 121 119 240 81 601 Carlow County 01054 054 Tinnahinch 017049001 186 176 362 111 2501 Carlow County 01053 053 Marley 017032001 194 173 367 121 801 Carlow County 01054 054 Tinnahinch 017049002 75 75 150 67 2901 Carlow County 01054 054 Tinnahinch 017049003 84 81 165 64 1601 Carlow County 01015 015 Ballyellin 017005002 105 99 204 71 601 Carlow County 01015 015 Ballyellin 017005001 115 108 223 70 901 Carlow County 01017 017 Borris 017008001 90 100 190 75 1901 Carlow County 01043 043 Sliguff 017045001 140 127 267 83 5

Cost of GIS and mapping

• Map data in vector format at 1000, 2500, 5000 scales €2.2m over 5 years

• Additional Geography Statistician• GIS software ≈ €40K for ARC GIS licence• Training

GIS Python Scripting

Costs

• Staff costs reduced from 53 persons years in 2006 to 33 in 2011

• GIS allowed us to automatically measure road lengths

• Travel allowances for Enumerators by correct calculation of KM – limited cost increase from €1.3M to €1.5M despite 10% increase in EAs and an increase of €300K in commuter tickets

• Better placement of field staff - nearly too good

Savings Using GIS

Some of the People behind the 2011 Census

Questions and Discussion