Understanding the 2011 Census Geographies December 2012

Transcription

1 Introduction Understanding the 2011 Census Geographies December Other useful documents: The release of the 2011 Census results has brought with it some changes to the geographies at which we display data. This guide, used alongside the Understanding the 2011 Census Geographies reference sheet will help you to understand these changes. If you require further information on geographies, please refer to the Office for National Statistics (ONS) Beginners Guide to Geography section on their website. Fundamental Changes Census Estimates Lincolnshire 2. Understanding 2011 Estimates Publish date: 17 December 2012 The 2011 Census geographies are created using the same building blocks as the 2001 Census Output Areas (OAs). Output areas are the lowest statistical geography and are designed to have similar populations to one another so that comparisons can be made between them. OAs.uk are aggregated to form all higher geographies in the 2011 Census, including Lower Super Output Areas (LSOAs) and Middle Super Output Web: Areas (MSOAs), which are also designed to have comparable populations. Table A in the appendix shows the thresholds for each of these geographies. Between 2001 and 2011 there has been a large change in population in many areas and as a result some OAs, LSOAs and MSOAs have had to be split or merged in order to maintain their comparable population levels. Figure 1 shows how this has affected Witham St Hughs, an area that has seen a significant increase in population due to housing development in the area. The population has increased from 108 in 2001 to 1,692 in 2011, and therefore the 2001 OA boundary containing the village has been split into five OAs. Figure 1: Example of splits to output area boundaries due to population change in Witham St Hughs

2 Output Areas (OAs) The 2011 OAs are largely the same as in 2001 (93% of OAs are unchanged), though some OAs have either been merged together to form one larger output area, or split into two or three to create additional output areas. The merging of OAs has only occurred where the population of a single OA has decreased since 2001 to below 100, and likewise the splitting of OAs only took place where the population has increased to over 625. In England and Wales, 2.6% of all 2001 output areas were either split or merged using 2011 data. The splitting process has occurred in many areas of the county which have seen population increases. Map 1 shows the areas where changes have taken place. This is most notably in areas where there has been extensive housing development since Parts of Lincoln, Spalding, Gainsborough, Skegness, Sleaford, Grantham, Market Rasen and Bourne have seen such increases. Some of the more rural areas have also been affected, such as Witham St Hughs, Long Sutton, Spilsby, Donington, Tattershall, Woodhall Spa and some of Lincoln s satellite villages. The process has resulted in the number of OAs in Lincolnshire increasing from 2,264 to 2,358 between 2001 and Map 1: Areas of change for Output Areas

3 Lower Super Output Areas (LSOAs) Lower Super Output Areas are typically comprised of between four and six Output Areas. These geographies are designed to be a higher level geography, more akin to Wards but with comparable populations. As some of the Output Areas have changed, this has meant a change in a small number of LSOAs. Merges have been applied where lower super output area population has fallen below 1,000 persons or 400 households. Splits have been applied where lower super output area population exceeds 3,000 persons or 1,200 households. In 2001 there were 413 LSOAs in Lincolnshire, due to the merging and splitting process, this increased to 420 LSOAs in The areas affected by these changes are highlighted in Map 2. The largest affected area lies to the South of Lincoln and includes LSOAs covering North Hykeham, South Hykeham, Bassingham and Witham St Hughs. Elsewhere in the county, Louth, Spalding and Bourne have all experienced splits where the population has outgrown the existing boundary. Map 2: Areas of change for Lower Super Output Areas

4 Middle Super Output Areas (MSOAs) Middle Super Output Areas typically comprise of five or six LSOAs and are the largest Output Area geography available from the 2011 Census. In Lincolnshire there are only two areas affected by boundary changes to MSOAs. Merges have been applied where MSOA population falls below 5,000 persons or 2,000 households. Splits have been applied where MSOA area population exceeds 15,000 persons or 6,000 households In 2001 there were 86 MSOAs in Lincolnshire. This increased to 88 in 2011 due to two MSOAs being split. As can be seen in map 3, these changes occurred in North Hykeham and in the area surrounding Boston. Map 3: Areas of change for Middle Super Output Areas

5 Wards The ONS have changed how statistics for wards are provided since the 2001 Census. Wards for the 2001 Census were exact fits to output areas i.e. they were comprised of a number of OA s, this allowed exact figures for the wards to be provided. Since 2001, however, the boundaries have changed in some areas for political reasons, some boundaries completely changing, others only shifting a few metres or taking in an extra road (see fig 2). Due to these political changes, these wards are no longer exactly comprised of Output Areas as the boundaries do not perfectly match. Due to this the data provided at ward level in 2011 is best fitted to the ward boundaries but is not an exact fit. It must be noted that only the data is best fitted the boundaries themselves will look the same as the 2007 boundaries on the Lincolnshire Research Observatory website. Map 4 highlights the areas where the Ward boundary has shifted since The last change to ward boundaries in Lincolnshire was in Most affected areas are Lincoln, Witham St Hughs and Bassingham area, Sleaford and areas to the East of Sleaford, Spalding, Gosburton and Whaplode. Map 4: Areas of change for Wards (last change in 2007)

6 The best fitting of output areas to wards is explained in figure 2. The left hand image shows the 2001 boundary in blue, with the current boundary change since 2001 in pink. The right hand image shows the area that is best fitted to the current ward boundary from output areas and therefore the area that data will be provided for. The pink sliver is the area of change since 2001 and would potentially disclose information at too low a level, so for 2011 the area that the data covers includes an additional OA to compensate for the boundary change. This does not physically change the ward boundaries, but shows the area that the data covers for that ward. Figure 2: Example of Ward changes and best fitting Higher Geographies Higher geographies such as Economic Zones, Local Authority Districts, NHS Localities and Clinical Commissioning Groups will remain unchanged. Other Geographies In addition to the changed geographies, the ONS will be releasing data at a new geography called workplace zones. Workplace zones and are designed to show areas with similar numbers of workforce in the area rather than residents. To date the ONS have released little further information on the workplace zones other than that they are best fitted from OAs and will be no larger than a MSOA. Other geographies will all be best fitted to OAs as per the wards and will include parishes, settlements, urban areas and nomenclature of units for territorial statistics (NUTS). The ONS website has further descriptions for all geographies provided for the Census. This information can be found at

7 Appendix Tables Table A: Office for National Statistics thresholds for 2011 Census geographies Geography Minimum Threshold Maximum Threshold Average (2011) Output Area Lower Super Output Area 1,000 3,000 1,614 Middle Super Output Area 5,000 15,000 6,543 Table B: Count of geographies in Lincolnshire at 2001 Census and 2011 Census Geography Count 2001 Count 2011 Change? Output Area 2,264 2,358 YES Lower Super Output Area YES Middle Super Output Area YES Ward YES (in 2007) District 7 7 NO Economic Zone N/A 13 N/A NHS Locality N/A 11 N/A Clinical Commissioning Group N/A 4 N/A Parish NO Indexing 2012 D. Drivers for Change 6. Environment 1. Business and Industry 7. Health and Care 2. Crime & Safety 8. Housing 3. Deprivation 9. Labour Market 4. Economy Education, Skills and Training 11. Unemployment Using the reference system (left), readers can identify how this document fits into sequence. The circled number relates to the Indexing reference (left). The number underneath is the document edition number.