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Ms H Verhoef Isibalo Symposium, Free State October 11, 2013.

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Presentation on theme: "Ms H Verhoef Isibalo Symposium, Free State October 11, 2013."— Presentation transcript:

1 Ms H Verhoef Isibalo Symposium, Free State October 11, 2013

2 Introduction Literature study Needs assessment Evaluation of 2001 output geographies Recommendations and specifications for the 2011 small area design

3 Why does geography matter? Geography: Where? Spatial relationships and distribution Visualisation

4 Nested hierarchy for the South African census of 2011

5 Census geography Enumeration Areas – Collection geography o Designed to manage fieldwork o Homogeneity according to residential type or land use – EA type

6 Census data Aggregated on different geographic levels o Generalisation o Loss of detail Modifiable Areal Unit Problem

7 MAUP illustrated Source: www.zonedesignsystems.com/intro4 The Modifiable Areal Unit Problem/Zone Design Systems.www.zonedesignsystems.com/intro4

8 Enumeration Area Population Range Total Population RangeNumber of 2011 EAs% 071156.9 1 to 1022062.1 11-10061515.9 101-20058425.6 201-30075557.3 301-40099509.6 401-5001282412.4 501-6001487514.4 601-7001303312.6 701-80088028.5 801-90056325.4 901-100033753.3 1001-200058765.7 >20013400.3 Total103576100.0

9 Output geography What are other countries doing? Problem with 2001 output geography o Very large physical areas o Island EAs/SAs

10 The problem with SA’s current output geography

11 Outcome of SAs’ user needs Census variablesAve scoreRank Total population8.31 Housing8.12 Total Households8.03 Employment / unemployment7.54 Education7.55 Income7.36 Water7.17 Energy7.18 Sanitation7.19 Population Group7.010 Age Groups6.811 Gender6.412 Goods & Services5.813 Agriculture5.614 Language5.315 Citizenship5.316 Migration5.217 Mortality5.018 Parental survival4.319

12 Two options for input in the creation of small areas for 2011 EAs: Inherit EA demarcation specifications and problems Geo-coded record data: Not all 2011 records were geo code-able to addresses or smallest land parcels Create building blocks such used in the UK or Canada ?

13 Options for the output geography design Same specifications as 2001 SAL - Same problems Same specifications as 2001, except change population minimum from 500 to 300 - Potentially better (but still island problems) Change specifications: - Find ideal tot pop within confidentiality frame - Test for the most wanted variables

14 Options for the output geography design (continue) Re-demarcate the vacant areas to eliminate all island EAs and limit physical size when merging EAs - potentially better shapes and area size Exclude vacant and populated areas with population below 10 - potentially better shapes and areas size NB: This option will result in non-contiguous coverage – suppressed areas blank

15 Census 2011 Small Areas As many as possible SAs = one EA, depending on the EA population size and acceptable level of confidentiality. The small areas should ideally be: as small as possible in terms of physical area and population size, as compact in shape as possible, as homogeneous as possible (EA type), fall within administrative boundaries.

16 South African hierarchies

17 Future research & development Creation of new building blocks Blocks or block-faces similar to what is done in Canada or the postman walks in the UK  Useful to create all other areas such as wards, voting districts, policing areas etc.  Sample frames Complete the address frame  Enable us to link census questionnaires to localities in stead of EAs  Create unique user determined output

18 Census data, publications and spatial files info@statssa.gov.za www.statssa.gov.za EA / PN & SA Spatial/geographic enquiries & comments helenev@statssa.gov.za


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