Ireland from Boundary Geography to Geo referenced Dwellings in Census 2011 Not a pointless process Joint UNECE/Eurostat Meetings on Population and Housing Censuses Friday 2 October 2015 Gerry Walker Central Statistics Office, Ireland

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,

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 K (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 boundaries Create 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 ( 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 publications had 7 maps 2011 publications had 95 maps 2011 dot maps SAPMAP now at small area 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

1 Km² Grid 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

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