Impact Assessment of Improved Immigration Estimates on Local Authorities in England and Wales

Transcription

1 Impact Assessment of Improved Immigration Estimates on Local Authorities in England and Wales Executive Summary As part of the Migration Statistics Improvements Programme, ONS has developed an improved methodology for estimating long-term to local authorities (LAs) in England and Wales. The first part of the report examines the impact of this improvement on the LA level estimates of. The second part focuses on the indicative impact of these improved estimates on the mid-year population estimates. The improved methodology, like the current methodology distributes the national estimates derived from the International Passenger Survey (IPS) to produce LA level estimates. Therefore, England and Wales IPS totals that are distributed are the same for both methodologies. However, each produces quite different sub-national estimates. The current methodology aims to make the best use of the UK destination information from the IPS and distributes this down to LA level through a series of intermediate steps. The final step uses a model-based approach to distribute down to individual LAs. The improved method uses the reason for migration information from the IPS to group migrants into streams (eg workers, students) which are then distributed directly to LAs using administrative sources. There are two main patterns of change moving from the current to the improved estimates: 1. There are important changes at the regional level with upward revisions in London, West Midlands, and Wales and downwards revisions in the North East, Yorkshire and The Humber, and the East of England. This pattern is due to the removal of Labour Force Survey (LFS) data to distribute from the national total to regions. 2. There is a pattern of downward revisions for large LAs in regional centres and upward revisions for smaller LAs adjoining these areas. This is thought to be due to a combination of the removal of the LA level groupings (known as intermediate geographies) and the modelling-based approach which has resulted in the removal of a residual centralising tendency in the estimates. However, the impacts on specific LAs are often complex and need to be understood both in terms of removing elements of the current methodology, and the sources and methods underpinning the improved method. While some of the changes to are quite large, most LAs see only small change to their population estimates with almost 90 per cent of LAs having a indicative population change between mid-2005 and mid-2010 of less than 2 per cent. This is because many LAs have levels that are small relative to their total population. However, there are some LAs where the population estimates have changed considerably. For example, Newham s indicative 2010 mid-year population estimate is more than 13 per cent higher while Boston has increased by 8 per cent. The indicative estimates for Cambridge, Kensington and Chelsea, and Oxford have quite large downward revisions and the report includes some additional validation of these outliers. 1

2 1. Introduction: This report is part of a package of documents describing improvements that have been made to the estimation of to local authorities (LAs) in England and Wales. The improved methodology uses administrative data sources to directly distribute the England and Wales long-term totals from the International Passenger Survey (IPS) to LAs. The approach is to split the IPS data into different streams, mainly by reason for migration (eg worker, student, other) and then relating each stream as closely as possible to the relevant administrative sources. Further details on the method are available from the report Improved Immigration Estimates to Local Authorities in England and Wales: Overview of Methodology, which is presented as part of this release package. Improved long-term total international estimates (LTIM 1 ) by local authority have been produced for each of the past five years (ie from mid-2006 to mid-2010 inclusive). In addition, a full set of mid-year population estimates has been produced that incorporate these improvements. This report has two main aims: 1. To provide a broad assessment of the impact of the improvements on the estimates for LAs within England and Wales, and the resulting impact on the mid-year population estimates. 2. To provide guidance and support to enable users to explore the more detailed tables and charts accompanying this package. ONS intends to use the improved method rolling forward from the 2011 Census-based mid-year estimates. ONS will not be revising official population estimates at this stage. The National Statistics Code of practice advises producers of statistics to avoid frequent revisions. The mid-year population estimates were last revised in May 2010 and will be revised again following publication of the 2011 Census results. Also, population estimates for the new methodology can only be produced back to 2006 and a revision would create a discontinuity to official series. Therefore current 2010-based mid-year population estimates (ie those published in June 2011) will remain the official series until these post-census revisions. However, ONS intends to incorporate these improvements into the 2010-based sub-national population projections for England which will be used for the next local authority funding settlement. Sub-national population projections for Wales will not be published until after the 2011 Census. To avoid confusion with the current official series, the estimates based on the improved methodology and the resulting impacts on the population estimates are referred as indicative estimates, and any differences between the current estimates and these indicative estimates are referred to as indicative revisions. The report comprises eight sections. Sections 2 to 6 focus on the area level impacts to. Section 7 examines the impact on the population estimates. Section 8 is an outlier analysis for several LAs where the indicative population estimates show some unusual results. 1 Long-term international migration (LTIM) is the most comprehensive measure of international migration and includes adjustments for asylum seekers and for switchers (i.e. those who change their migration intentions.) 2

3 2. High level impact on estimates The improved method distributes the same IPS data as the current method, so there is no change to the England and Wales IPS totals. There is only a very minor change resulting from a correction to the asylum seeker adjustment in There are some small changes at country level with an indicative upward revision for Wales of 9700, and a decrease for England of -9,400 (Table 2.1). There are also changes at regional level within England. The total into London from 2006 to 2010 has an indicative upward revision of 16 percent while the West Midlands increased by just over 15 per cent. The largest indicative downward revision is for Yorkshire and The Humber (-23 per cent), followed closely by the East of England (-22 per cent) and the North East (-21 per cent). Table 2.1 Cumulative impact of improvements on countries and regions, 2006 to 2010 Area Current LTIM estimate LTIM estimate revision Percentage indicative revision England 2,531,200 2,521,800-9, % North East 95,300 75,700-19, % North West 214, ,600 5, % Yorkshire and The Humber 236, ,600-54, % East Midlands 153, ,800 7, % West Midlands 167, ,300 25, % East of England 275, ,400-59, % London 813, , , % South East 391, ,900-24, % South West 183, ,800-20, % Wales 71,900 81,700 9, % England and Wales 2,603,100 2,603, % * Estimates have been rounded to hundreds but percentages have been calculated from unrounded data. Totals may not sum due to rounding. These country and regional level changes need to be understood in the context of removing a key element of the current methodology, namely the use of recent migrant data from the Labour Force Survey (LFS) to distribute to UK countries and regions. The rationale underpinning this methodology is that IPS migrant data is based on intentions and there is evidence of a tendency for migrants to the UK to state London as their main destination, but to actually settle in another part of the country (ONS, 2007). This is commonly referred to as centralising tendency. Comparisons between the 2001 Census, IPS and LFS migrant data show that the LFS better matches the regional distribution of 2001 Census migrants than the IPS. In theory, a household survey such as the LFS should be better able to record actual migrant destinations. There are however a number of weaknesses with the LFS. It is based on a smaller sample than the IPS and it misses important migrant groups, such as international students living in halls of residence. There are also definitional differences with the UN definition of a long-term migrant used by the IPS 3. The interaction of these factors and their impact on estimates are complex and not fully understood, but the distributions based on administrative source suggest that the current method distributes too many migrants out of London into other areas of the country. 2 This is an ONS processing correction and is the not the result of a change to the underlying data. 3 These issues are discussed further in Section 9.3 in the accompanying report: Improved Immigration Estimates to Local Authorities in England and Wales: Overview of Methodology 3

4 3. Impacts at local authority level The full set of impacts down to local authority level is shown in Table A: Local Authority Immigration Impacts by Year ( ) under the Tables and Charts section of this release package. The top 20 increases and decreases resulting from the indicative revisions is a simple, but effective, way of illustrating the main impacts of the improved method at LA level. The changes can be presented in both absolute terms, where larger LAs tend to dominate, but also in percentage terms which tends to feature smaller LAs. The full set of top 20 tables for each year is available in Table B: Top 20 largest upward/downward indicative revisions to under the Tables and Charts section of this release package. 3.1 Top 20 indicative LA increases The LAs with the largest upward indicative revision to in absolute terms are concentrated in London. In mid-2006, eight of the top 20 increases are London boroughs rising to 16 out of 20 by mid Over the five years the top seven places are all London boroughs and overall they fill 13 of the top 20 places (Table 3.1). The cumulative indicative revision for Newham (2006 to 2010) is almost twice that of Brent, the next largest upward revision. Newham also has the biggest upward revision in every year except for mid After London, the West Midlands features the most LAs in the top 20 with Herefordshire, Coventry and Sandwell, all appearing in three of the five years. Boston in the East Midlands is the only LA outside of London that appears in the Top 20 increases in every year. Table 3.1: Top 20 LA upward indicative revisions to (absolute), cumulative 2006 to 2010 Local Authority Region Current estimate estimate revision Percentage indicative revision Newham London 33,200 67,100 33, % Brent London 33,400 51,100 17,700 53% Haringey London 22,200 38,500 16,300 73% Islington London 27,700 38,400 10,600 38% Tower Hamlets London 36,800 47,100 10,300 28% Enfield London 13,900 22,300 8,400 60% Waltham Forest London 24,800 32,000 7,200 29% Coventry West Midlands 26,200 33,000 6,800 26% Hounslow London 32,900 38,900 6,000 18% Boston East Midlands 2,300 7,500 5, % Hackney London 18,100 23,000 4,900 27% Sandwell West Midlands 6,100 10,700 4,500 74% Southwark London 39,300 43,400 4,200 11% Hillingdon London 16,300 20,400 4,100 25% Aylesbury Vale South East 3,900 8,100 4, % Guildford South East 11,800 15,700 3,900 33% Lewisham London 19,800 23,700 3,900 20% Barnet London 31,500 35,300 3,700 12% Bolton North West 4,600 8,200 3,700 81% Herefordshire, County of West Midlands 3,400 7,000 3, % * Estimates have been rounded to hundreds but percentages have been calculated from unrounded data ** Immigration estimates are based on LTIM. 4

5 In percentage terms the majority of the LAs with the largest upward indicative revisions are in the North West and East Midlands (Table 3.2). There are nine LAs from the North West over five years combined, with six from the East Midlands. Corby and West Lancashire are the two LAs that feature in the Top 20 in every year, and they also fill the top two places over the five years combined. LAs which feature in four of the five years are Boston, Chorley, Rossendale, South Holland, South Ribble and Swale. All these LAs are in the North West or East Midlands, except Swale. In the majority of cases, the LAs with the highest percentage increases have a cumulative five year flow of less than 1000, and so an increase of just a few hundred each year can result in a high percentage increase. Table 3.2: Top 20 LA upward indicative revisions to (percentage), cumulative 2006 to 2010 Local Authority Region Current estimate estimate revision Percentage indicative revision Corby East Midlands 600 2,800 2, % West Lancashire North West 500 2,300 1, % Swale South East 900 3,400 2, % Chorley North West 500 1,600 1, % Mansfield East Midlands 600 2,000 1, % Boston East Midlands 2,300 7,500 5, % South Ribble North West 400 1, % Fenland East of England 1,600 4,500 2, % Rossendale North West % South Holland East Midlands 1,700 4,600 2, % St. Helens North West 900 2,200 1, % Sefton North West 1,700 4,100 2, % Hyndburn North West 500 1, % North Kesteven East Midlands 1,200 2,800 1, % West Somerset South West % Tamworth West Midlands % Torfaen Wales % Wigan North West 2,300 5,000 2, % Derwentside North East 500 1, % Warrington North West 2,600 5,500 2, % * Estimates have been rounded to hundreds but percentages have been calculated from unrounded data ** Immigration estimates are based on LTIM. 3.2 Top 20 indicative LA decreases Whereas the largest upward indicative revisions in absolute terms are concentrated in London, the LAs with the largest downward indicative revisions are spread more evenly across England and Wales (Table 3.3). From mid-2006 to mid-2010 combined, LAs in Yorkshire and The Humber fill five of the top 20 places, followed by the South East with four, and the East of England with three places. LAs that appear in the top 20 with the biggest downward revisions in all five years are Cambridge (East of England), Manchester (North West), Bristol (South West), Oxford (South East) and Norwich (East of England). Leeds (Yorkshire and The Humber), Sheffield (Yorkshire and The Humber) and Reading (South East) appear in the top 20 in four out of the five years. Many of these LAs are university towns or cities. Westminster and Kensington & Chelsea are the two London Boroughs that are exceptions to the general pattern of upward revisions in London (see Table 3.1). 5

6 Table 3.3: Top 20 LA downward indicative revisions to (absolute), cumulative 2006 to 2010 Local Authority Region Current estimate estimate revision Percentage indicative revision Manchester North West 85,200 55,300-29,900-35% Cambridge East of England 41,500 20,400-21,100-51% Leeds Yorkshire and The Humber 59,700 42,200-17,500-29% Bristol, City South West 42,300 27,300-14,900-35% Sheffield Yorkshire and The Humber 45,300 31,800-13,600-30% Norwich East of England 22,900 10,900-12,000-52% Oxford South East 38,700 28,000-10,700-28% Westminster London 60,400 50,300-10,200-17% Reading South East 27,100 17,100-10,000-37% Newcastle upon Tyne North East 39,300 30,300-9,100-23% Kensington and Chelsea London 35,400 27,600-7,700-22% Bradford Yorkshire and The Humber 31,700 24,300-7,400-23% Leicester East Midlands 34,600 27,700-7,000-20% Portsmouth South East 18,500 11,800-6,700-36% Colchester East of England 17,700 11,000-6,700-38% Nottingham East Midlands 35,700 29,600-6,100-17% Southampton South East 29,200 23,200-6,000-21% York Yorkshire and The Humber 16,100 10,600-5,500-34% Durham North East 12,100 6,600-5,500-45% Kingston upon Hull Yorkshire and The Humber 17,700 12,500-5,200-29% * Estimates have been rounded to hundreds but percentages have been calculated from unrounded data ** Immigration estimates are based on LTIM. The East of England has the most LAs with high percentage decreases with half of all the top 20 places for total mid-2006 to mid-2010 period (Table 3.4). However, Richmondshire, in Yorkshire and The Humber, is the only LA which appears in all five years. Both Richmondshire and Forest Heath (which has the fifth largest % decrease) are LAs with substantial armed forces populations. LAs which appear in four of the five years are Basildon, Brentwood, Forest Heath and Isles of Scilly. The first three of these LAs are all in the East of England. Cambridge, Norwich and Durham are the only LAs that are in the Top 20 decrease in both absolute and percentage terms. 6

7 Table 3.4: Top 20 LA downward indicative revisions to (percentage), cumulative 2006 to 2010 Local Authority Region Current estimate estimate revision Percentage indicative revision Isles of Scilly South West % Richmondshire Yorkshire and The Humber 5,000 1,700-3,300-66% Basildon East of England 7,600 3,000-4,600-61% Brentwood East of England 3,800 1,500-2,300-60% Forest Heath East of England 5,400 2,400-3,000-56% Norwich East of England 22,900 10,900-12,000-52% Cambridge East of England 41,500 20,400-21,100-51% South Tyneside North East 5,300 2,700-2,700-50% Purbeck South West 1, % Craven Yorkshire and The Humber 1, % Watford East of England 9,000 4,700-4,200-47% Rushmoor South East 7,700 4,100-3,600-47% Maldon East of England 1, % Durham North East 12,100 6,600-5,500-45% Chelmsford East of England 7,600 4,200-3,400-45% Stevenage East of England 3,300 1,800-1,500-44% Malvern Hills West Midlands 2,500 1,400-1,100-43% Epsom and Ewell South East 4,200 2,600-1,600-39% Thurrock East of England 8,000 4,900-3,100-39% Alnwick North East % * Estimates have been rounded to hundreds but percentages have been calculated from unrounded data ** Immigration estimates are based on LTIM Conclusion The patterns observed in these tables are the product of moving between two distinct and sometimes complex methods. Understanding these patterns requires some knowledge of not just the improved methods and data sources for distributing flows, but also the current distributional method. There are different factors driving change at different levels of geography and they impact on both the direction and magnitude of change. Some of the regional level factors have already been touched on, but there are also other important aspects that need to be understood. The following three sections aim to shed further light on both the indicative estimates and differences with the current estimates. 7

8 4. Comparison of the improved estimates against administrative sources The GP patient register Flag 4 4 counts and National Insurance number (NINo) allocations to foreign nationals 5 are the two broad coverage administrative sources where comparisons with ONS estimates of LTIM can be usefully made. However, there are well documented differences between LTIM and these sources in terms of definitions, coverage, and timeliness. LTIM estimates are based on the UN definition of a long-term migrant, which is someone who changes their country of usual residence for more than a year. In contrast, the published counts from the administrative sources will include those residing in the UK for less than a year. Despite these differences, comparisons of the estimates with the published administrative counts can demonstrate that the new method is indeed an improvement on the existing method. Even if the levels are different, the trends in the administrative data can be examined to see how well they track the improved ONS estimates. The comparisons with the Flag4 counts are particularly useful as it is the broadest coverage source, yet it is used to distribute less than 15 per cent of the indicative estimate. Therefore, to a certain degree it can be used to validate the indicative estimates. The relative differences between the estimates and the administrative counts between areas can also help to understand the particular characteristics of between areas. For example, the NINo counts will tend to be higher in areas dominated by workers and lower in areas dominated by students. Table 4.1 shows the ONS England and Wales long-term total international migration (LTIM) estimate compared with the Flag 4 counts from the GP patient register and National Insurance number (NINo) allocations to foreign nationals. Flag 4 counts are about 50,000 to 100,000 more than LTIM, with the gap widening over time. There is anecdotal evidence to suggest that the increasing Flag 4 count in recent years may be due to organised local efforts to register immigrants, some of whom may have been living in England and Wales for a number of years. The NINo counts are also higher than LTIM, but are more volatile than the Flag 4s. There is a noticeable peak in 2006/07 which was mainly driven by a peak in registrations of A8 6 nationals (ONS, 2008a). The most likley explanation for the administrative counts being higher is that they include short-term migrants that are excluded from LTIM. Table 4.1: Comparison of LTIM with NINo and Flag 4 counts, England and Wales, mid-2006 to mid / / / / /10 LTIM NINo Flag 4 Sources: ONS, DWP, NHS 4 Flag 4s are codes within the Patient Register Data Service (PRDS) system which indicate that someone who has registered with a GP in England and Wales was previously living overseas. 6 A8 countries are the eight Central and Eastern European countries that acceded to the EU on 1 May

9 At the England and Wales level, there is virtually no difference between the current and the improved LTIM estimates (apart from a minor correction to the asylum seeker adjustment) as both methods distribute from the same IPS data. However, these comparisons can be replicated at lower levels of geography and since the methods distribute this total differently, they will produce different results. Figure 4.2 shows the equivalent comparisons for each of English region and Wales separately. As discussed in Section 2, the current method uses data from the Labour Force Survey (LFS) to distribute IPS flows to UK countries and regions within England. Therefore, comparisons with the current indicative estimates can be used to further evaluate this aspect of the current methodology. The current estimates often show volatile trends. In the North East, the current estimates show a sharply rising trend which is not observed in either the Flag 4 or the NINo data. The current estimates for the North West show a gradually rising trend while the administrative sources point to a gradual decline. In contrast, the current estimate for London suggests has stagnated over the past five years, while the administrative sources both point to increasing levels of. The East Midlands is another example where the current estimate is volatile, dropping well below the administrative sources and the improved indicative estimate during 2009 and In comparison, the indicative estimates track below the Flag 4 counts fairly consistently following the broad pattern at the England and Wales level, apart from Wales where the indicative estimates are higher in 2006 and 2007, These patterns show that the LFS is not particularly good at capturing recent migration trends. This is partly a function of the small sample of migrants from the LFS. Also, since the LFS migrants are clustered in households, which increase the volatility of the estimates. In contrast, the improved regional level estimates are less volatile and more closely follow the trends seen in the administrative data, particularly for the Flag4 counts. A tool for users to produce charts for individual LAs is in Table C: Comparisons of current and indicative estimates with administrative sources under the Tables and Charts section of this release package. 9

10 Figure 4.2: Comparison of LTIM with NINo and Flag 4 counts, English Regions and Wales, mid-2006 to mid-2010 North East North West / / / / / / / / / /10 Current Improved Nino Flag 4 Current Improved Nino Flag 4 Yorkshire and The Humber East Midlands / / / / / / / / / /10 Current Improved Nino Flag 4 Current Improved Nino Flag 4 West Midlands East of England / / / / / / / / / /10 Current Improved Nino Flag 4 Current Improved Nino Flag 4 London South East / / / / / / / / / /10 Current Improved Nino Flag 4 Current Improved Nino Flag 4 South West Wales / / / / / / / / / /10 Current Improved Nino Flag 4 Current Improved Nino Flag 4 10

11 5. Analysis of improved methodology by broad stream The improved methodology uses administrative sources to distribute different categories of migrants into separate streams that are then combined to produce a total estimate for each LA. These stream totals allow the particular characteristics of migration into a LA to be better understood. The methodology uses a total of 15 streams (excluding asylum seekers), but for ease of analysis these are consolidated into four broad streams. The methodology for estimating asylum seekers has not changed, but these are also included to show how the LTIM estimate is broken down, thus giving five streams overall. These broad streams are: Workers (including non-uk born returning migrants) Students (including non-uk born returning migrants) Returning Migrants, UK-born (ie all those born in the UK who have been usually resident outside of the UK and are now returning to live in the UK) Other migrants (Including all children, those over 60 years of age, and other non-working dependents) Asylum Seekers (based on the existing Asylum Seeker adjustments) It is important to note that these broad stream subtotals do not correspond directly to the published IPS and LTIM statistics of by main reason for migration. The methodology is not designed to produce statistics that correspond to these existing concepts, but rather to provide the closest possible mapping between the IPS data and the administrative data. For example, the 'workers' stream includes some migrants who have not given work as their main reason for migration. Certain characteristics of these migrants may mean that they are considered likely to work and will therefore appear in the administrative sources together with those who have given work reasons in the IPS. Further information of the methodology explaining these broad stream totals is available in the report Improved Immigration Estimates to Local Authorities in England and Wales: Overview of Methodology. Thus, it is important to note that these stream totals are artefacts of the improved methodology and are only indicative of the composition of migrant flows into an LA. They should not be interpreted as being definitive estimates of say, migrant workers into an area. However, they can be used when making comparisons with other areas in terms of the relative importance of each stream. Table 5.1 shows the composition by broad stream at regional level for the five years for which indicative estimates have been produced. Tables 5.1 Region/country composition of flows by broad streams, combined Region estimate Workers Students Returning migrants (UK born) Asylum Seekers Others North East 75,700 28% 41% 12% 9% 10% 100% North West 220,600 38% 27% 13% 8% 14% 100% Yorkshire & The Humber 182,600 35% 29% 11% 8% 16% 100% East Midlands 161,800 43% 28% 11% 3% 15% 100% West Midlands 193,300 39% 30% 10% 7% 15% 100% East 215,400 47% 22% 14% 1% 15% 100% London 942,800 49% 27% 6% 4% 13% 100% South East 366,900 41% 26% 16% 1% 15% 100% South West 162,800 39% 25% 20% 2% 15% 100% Wales 81,700 32% 37% 13% 6% 12% 100% Total % 28% 11% 4% 14% 100% Total * Values in table may not sum due to rounding 11

12 This illustrates that international migration to London and the East of England is characterised by work whereas migration into the North East and Wales for study reasons is relatively more important. Only six per cent of migration flows into London from 2006 to 2010 were UK born returning migrants whereas in the South West the proportion was 20 per cent. There are no real extremes in the others stream apart from the North East which is somewhat lower than average. More detailed analysis at LA level can shed further light on these patterns. Table 5.2 shows the total flows into each LA within the North East from 2006 to The percentages for each broad stream have been grouped into quintiles at the England and Wales level. This enables the composition of each LA to be analysed together with the relative importance of each broad stream component. This enables the particular characteristics of migration into areas to be observed more clearly. For example, the relatively high student flows into the North East are clustered into a small number of local authorities (Newcastle, Durham and Sunderland). However, these three LAs are all in the bottom quintile in terms of the importance of the others stream. A likely explanation is that student migrants are less likely to be accompanied by dependents than other migrant groups. This then helps explain the patterns observed for the North East in Table 5.1. The full set of analyses down to local authority level is shown in Table D: Analysis of Estimates by Broad Stream under the Tables and Charts section of this release package. Table 5.2 Composition of flows by broad streams in North East, combined Local Authority Total Workers Students Returning migrants (UK born) Asylum Seekers Others Gateshead 4,400 36% 23% 11% 15% 14% (England and Wales) Newcastle upon Tyne 30,300 21% 59% 5% 7% 8% 1st quintile North Tyneside 2,900 31% 16% 29% 12% 12% 2nd quintile South Tyneside 2,700 51% 7% 17% 11% 14% 3rd quintile Sunderland 8,200 25% 52% 9% 8% 7% 4th quintile Hartlepool % 2% 26% 7% 16% 5th quintile Middlesbrough 6,500 32% 27% 5% 20% 16% Values showing 0% are Redcar and Cleveland 1,100 33% 9% 42% 6% 10% Excluded from this analysis Stockton-on-Tees 3,400 30% 12% 23% 21% 14% Darlington 2,300 51% 8% 17% 8% 15% Chester-le-Street % 10% 32% 0% 15% Derwentside 1,100 64% 6% 18% 0% 12% Durham 6,600 16% 63% 12% 0% 10% Easington % 7% 26% 8% 12% Sedgefield % 6% 23% 4% 13% Teesdale % 4% 46% 0% 15% Wear Valley % 7% 22% 1% 14% Alnwick % 3% 49% 0% 11% Berwick-upon-Tweed % 3% 24% 0% 12% Blyth Valley % 9% 41% 0% 11% Castle Morpeth % 6% 52% 6% 12% Tynedale % 5% 45% 0% 10% Wansbeck % 10% 44% 0% 13% Total 75,700 28% 41% 12% 9% 10% * Quintile grouping have been calculated on an England and Wales basis * Percentages are calculated from unrounded data 12

13 6. Analysis of current and improved by geography The current method for estimating to LAs involves distributing the England and Wales IPS total down through several levels of geography. The total is first distributed to regional/country level using data about recent migrants from the Labour Force Survey (LFS). These area totals are then distributed to groupings of local authorities known as intermediate geographies (referred to as New Migration Geographies for, or NMGis). This is the lowest level to which the IPS data is used directly in the current method. The NMGi totals are then distributed to LAs using a regression model based on the relationships between the LA level IPS data and a range of data sources 7. An overview of the current distributional approach is shown in Annex A. The improved method distributes directly to LAs from IPS sub-total estimated at the England and Wales level (See Annex B). Although regions and NMGis are not used in the improved methodology, they are useful in terms of gaining an understanding of the change from the current to the improved method and why the patterns of change vary between LAs. This change can be analysed in terms of the change attributable at different levels of geography. Table 6.1 shows an example of this analysis for all LAs within the North East region of England. Table 6.1: Analysis of Current and Improved Immigration Estimates 8 within the North East, mid-2006 to mid-2010 combined Local Authority NMGi code Current estimate* Improved indicative estimate* Total ision % ision Attributable at Region level % ision Attributable at NMGi level % ision Attributable at LA level Blyth Valley NE % % -5-1% % Castle Morpeth NE % % -9-1% 21 3% Wansbeck NE % % -6-1% 39 9% Gateshead NE1 3,229 3, % % -42-1% 1,219 38% Newcastle upon Tyne NE1 37,273 28,186-9,087-24% -8,227-22% % % North Tyneside NE1 2,859 2, % % -37-1% % South Tyneside NE1 5,019 2,361-2,658-53% -1,108-22% -66-1% -1,485-30% Hartlepool NE % % 15 2% % Middlesbrough NE2 6,762 5,205-1,557-23% -1,493-22% 113 2% % Redcar and Cleveland NE2 1,208 1, % % 20 2% 43 4% Stockton-on-Tees NE2 2,578 2, % % 43 2% % Darlington UA NE2 2,028 2, % % 34 2% % Chester-le-Street NE % % 6 2% 29 8% Derwentside NE , % % 9 2% % Durham NE2 12,089 6,623-5,466-45% -2,668-22% 202 2% -2,999-25% Easington NE % % 6 2% % Sedgefield NE % % 7 2% % Teesdale NE % % 5 2% -19-6% Wear Valley NE % % 6 2% % Alnwick NE % % 10 2% % Berwick-upon-Tweed NE % % 11 2% -22-3% Tynedale NE % % 14 2% 4 0% Sunderland NE2 9,061 7,628-1,433-16% -2,000-22% 151 2% 416 5% % * LTIM estimate excluding Asylum Seekers 7 Further details on the current method are available in the following report: Estimating international long-term by local authority (LA) Office for National Statistics. 8 Estimates are shown at unit-level to show the change effects more clearly. However, these estimates can not be guaranteed to be as exact as the level of detail implied by unit-level data. 13

14 This analysis shows that over the period from mid-2006 to mid-2010 the improved methodology allocates 22 per cent fewer immigrants to the North East than the current methodology. Therefore, the indicative revision that is attributable to regional effects to all LAs within the North East is a decrease of 22 per cent. There are two NMGi groupings in the North East (ie NE1 and NE2). The table shows how much of the indicative revision can be attributed to way LAs are grouped into NMGis in the current method, once the regional effect is removed. After the regional effects are accounted for the NE2 group is allocated a slightly higher proportion of immigrants under the improved method while NE1 is given slightly less. The indicative revision attributable at NMGi level will always balance out within the regional total. In conceptual terms, the differences at this level reflect how well the IPS estimates for the NMGi groupings compared with a direct distributional approach. Although the indicative revision attributable at this level is relatively small in this example, there are much larger differences in some other regions. Finally, the remaining difference is the change that is attributable at LA level. This is mainly the effect of moving from the current model-based approach to the direct distributional approach once the regional and NMGi effects are removed 9. The change attributable at LA level will always balance out at NMGi level. In conceptual terms, the difference reflects how well the regression model used to allocate migrants to LAs compared with a direct distributional approach. This information can be combined to form a clearer picture of what is driving the changes for any particular local authority. For example, the total estimate for Durham between 2006 and 2010 is reduced overall by 45 per cent. This comprises a 22 per cent reduction attributable to regional effects, a two per cent increase attributable to NMGi effects, and a 25 per cent reduction attributable to LA level effects. For a number of NMGis there is a common pattern of change at LA level moving from the current to the improved method where the estimate is lower for the main population centre (or centres) but is higher for the smaller LAs within the NMGi. This appears to be due to a residual IPS centralising tendency effect within regions which is very similar to that which occurs nationally. In simple terms, it is a tendency for migrants to state an intention to live in a well-known city, rather than less well known area nearby. The current method was initially designed to address centralising tendency at this level. From 2007 to 2010 the final distribution step from NMGis to LAs used a 2001 Census data. In 2010 this was replaced with a regression model based approach, which used more up to date sources. However, since the approach models IPS survey data it appears that some centralising tendency in the data is being modelled into the current estimates. An example is shown in Table 6.2 of the EM5 NMGi which contains Leicester. The pattern suggests that the IPS model based approach put too many migrants in to Leicester and not enough into other local authorities within the EM5 grouping. Therefore, Leicester is revised down but the other LAs in the grouping are revised upward. 9 Some of the change at this level is also due changes in rounding. 14

15 Table 6.2: Analysis of Current and Improved Immigration Estimates within the EM5 group, mid-2006 to mid-2010 combined Local Authority NMGi code Current estimate* Improved indicative estimate* Total ision ision Attributable at Region level ision Attributable at NMGi level ision Attributable at LA level Leicester UA EM5 32,520 25,556-6,964-21% 1,727 5% % -8,378-26% Blaby EM , % 31 5% -6-1% % Charnwood EM5 6,698 9,836 3,138 47% 356 5% -64-1% 2,847 43% Harborough EM , % 33 5% -6-1% % Hinckley and Bosworth EM5 1,116 1, % 59 5% -11-1% % North West Leicestershire EM , % 43 5% -8-1% % Oadby and Wigston EM , % 49 5% -9-1% % Corby EM ,744 2, % 30 5% -5-1% 2, % East Northamptonshire EM , % 41 5% -7-1% % Kettering EM5 1,241 2,242 1,001 81% 66 5% -12-1% % % % % % * LTIM estimate excluding Asylum Seekers 15

16 7. Impacts on mid-year population estimates These indicative figures have been used to produce a set of indicative mid-year population estimates. However, there are also other components of population change that have been revised and incorporated into these indicative estimates. Emigration is affected because the current methodology for estimating emigration uses a regression model which has as one of its co-variates 10. Therefore, although the emigration methodology has not fundamentally changed, the values for emigration have been updated. ONS has also taken the opportunity to make three minor corrections to the current estimates: i) A correction to the post-study student adjustment that was removing too many people from student areas and into post-study destinations. This adjustment uses data from the Higher Education Statistics Agency (HESA), but the correction is the result of an ONS processing error. This correction affects all years from 2006 to ii) A correction to the mid-2009 England and Wales emigrant visitor switcher 11 adjustment (+11361). iii) A correction to mid-2009 asylum seeker immigrant adjustment (+322) and the mid-2009 asylum seeker emigration adjustment (+571). These corrections are not large enough to affect policy making, which under the National Statistics Code of Practice would have required an unscheduled revision to the official series. Nonetheless, they have been incorporated into the indicative population estimates to produce the best possible set of figures. The total cumulative revision by component of change is shown in Table 7.1 by country and region. Unsurprisingly, dominates the other components of change and accounts for the most of the total cumulative revision. Reconciliation adjustments are primarily due to rounding. This is predominantly associated with the distribution of flows from the Republic of Ireland, which were processed separately up until 2008 and were broken down to non-integer values. There is also a small amount of other rounding, as well as adjustments to reconcile the sum of the local authority totals to the national total. Table 7.1 Cumulative revision to mid-year population estimates by type of component of change by country/region Area International Migration Inflow Outflow Net Net Internal Migration Reconciliation Adjustment Total cumulative revision England -9,400 11,200-20, ,700 North East -19, , ,600 North West 5,600 2,400 3, ,300 Yorkshire and The Humber -54, , ,700 East Midlands 7, , ,100 West Midlands 25,700 1,100 24, ,200 East of England -59,900 1,200-61, ,000 London 129,800 1, ,100-1,800-1, ,200 South East -24,100 1,800-26,000 1, ,700 South West -20,500 1,500-22, ,400 Wales 9, , ,100 England and Wales ,900-11, ,600 * Values in table may not sum due to rounding 10 Some co-variates of the emigration model have been updated including internal migration and new LFS data. 11 Visitor switchers are those in the IPS who are state an intention to stay for less than 12 months, but actually stay longer and therefore need to be counted as long-term migrants. 16

17 The internal migration changes show a net decrease for London of 1,800 and net increases for most other regions. This pattern is due to the post study student adjustment correction which tends to allocate student moves from post-study destinations such as London and into to student areas. This pattern becomes more pronounced when analysing the LA level data The full set of population estimates by age and sex are shown in Tables F1 to F5 and Tables G1 and G2 in the Tables and Charts section of this release package. The components of change broken down to LA level are shown in Table I in the Tables and Charts section of this release package. The average absolute indicative revision to for the 376 pre-2009 LAs over five years is The equivalent figure for emigration is 259. For just over half of LAs the revision to explains least 80 per cent of the revision to net migration and for all but 47, it explains at least 50 per cent. In approximately 68 per cent of LAs the change moves in the same direction so that increased is accompanied by increased emigration, or decreased is coupled with decreased emigration. In conclusion, although the detailed interactions between and emigration revisions for individual LAs are complex, the revisions to LA net migration are onj the whole, driven mainly by the revisions to. 7.1 Distribution of LA level impacts (based on pre-2009 LAs) Figure 7.1 shows the overall indicative revisions for the 2010 population estimates in terms of percentage change. Most LAs are not greatly impacted with around 90 per cent of LAs having an indicative revision of less than 2 per cent of the current 2010 mid-year population estimate. Close to half of all LAs have a small upward indicative revision of between 0 and 1 per cent. Almost 64 per cent of LAs are revised upward but only 13 LAs are revised upward by more than 2 per cent. In contrast, of the 36 per cent that are revised downward, twice as many (26 LAs) are revised by more than 2 per cent. In summary, a large number of LAs are revised upwards slightly which is offset by a relatively large number of LAs that are revised down by more. This asymmetrical pattern is largely be explained by the residual centralising tendency effects of the current methodology being corrected by the improved distribution method. As discussed in section 6, there is recurring pattern of being revised down in large population centres offset by small upward revisions in smaller nearby LAs. This pattern is simply reflected in the mid-year population estimates. 17

18 Figure 7.1 Distribution of percentage indicative revisions for 2010 MYEs, England and Wales (pre-2009 LAs) 7.2 Upward indicative revisions to mid-year population estimates The top 20 largest upward indicative revisions to the 2010 mid-year population estimates are shown in Table 7.2. Half of those in the top 20 are London Boroughs with a small concentration in the East Midlands (Boston, South Holland and Corby). The remainder are spread out across England and Wales. Newham stands out with a very large upward revision of over 13 per cent. It is also the highest in absolute terms (32,000), which is more that twice that of the next largest upward revision (Brent with 15,800). However, the size of the revisions tail off quickly with those near the bottom of the table making relatively small gains. 18

19 Table 7.2 Top 20 upward revisions to the 2010 mid-year population estimates: LA Name 2010 mid-year population ision mid-2010 ision mid-2010 (%) 2005 midyear population Population change, 2005 to 2010 (%) Published Published Newham 240, ,100 32, % 243, % 11.8% Boston 59,000 63,900 4, % 58, % 8.7% Haringey 225, ,900 13, % 224, % 6.5% Brent 256, ,400 15, % 257, % 5.7% Tower Hamlets 237, ,700 10, % 214, % 16.2% Islington 194, ,200 8, % 184, % 9.5% South Holland 84,600 87,400 2, % 81, % 6.9% Corby 55,800 57,600 1, % 53, % 7.6% Fenland 91,900 94,500 2, % 89, % 6.2% Waltham Forest 227, ,300 6, % 218, % 6.6% Enfield 294, ,600 7, % 283, % 6.8% Lancaster 141, ,200 3, % 139, % 3.0% Hounslow 236, ,900 5, % 221, % 9.2% Barking & Dagenham 179, ,300 3, % 167, % 9.7% Hackney 219, ,500 4, % 208, % 7.1% Herefordshire UA 179, ,800 3, % 177, % 3.3% Wrexham UA 133, ,100 2, % 130, % 4.7% Mid Bedfordshire 136, ,100 2, % 129, % 7.5% Coventry 315, ,700 6, % 303, % 6.0% Guildford 137, ,500 2, % 130, % 7.0% The impact of these indicative revisions on population change has been calculated by comparing the levels of the 2010 published and indicative population estimates with the 2005 mid-year estimates. This is the last year before the improvements have been applied and so can be used as benchmark for measuring how both the current and the improved methods estimate population growth. For the top four LAs (Newham, Boston, Haringey, and Brent), the difference is very marked, moving from low or negative population growth under the current method to strong growth under the improved method. Tower Hamlets was already showing strong population growth under the current method and has increased further under the improved method. 7.3 Downward indicative revisions to mid-year population estimates The top 20 largest downward indicative revisions to the 2010 mid-year population estimates are shown in Table 7.3. Cambridge has a very large downward revision of 16 per cent and although the size of these revisions tail off somewhat, they are still larger than the equivalent upward revisions in the previous table. As discussed earlier, this appears to be mainly due to the removal of residual centralising tendency effects of the previous methodology and a number of these LAs have 19

20 previously been identified as positive centralising LAs. (ie Cambridge, Oxford, Reading, Manchester, Westminster, Kensington & Chelsea, Bristol, and Newcastle upon Tyne) (see ONS, 2007). Most of the others are in the East of England, Yorkshire and The Humber, or the North East, which have the largest downward revisions to at the regional level. Table 7.3 Top 20 downward indicative revisions to the 2010 mid-year population estimates: LA Name 2010 mid-year population ision mid-2010 ision mid-2010 (%) 2005 midyear population Population change, 2005 to 2010 (%) Published Published Cambridge % % -4.7% City of London % % 23.4% Norwich % % 4.4% Isles of Scilly % % -7.3% Oxford % % -0.5% Reading UA % % 1.1% Manchester % % 5.2% Richmondshire % % 1.8% Durham % % 5.5% Watford % % 3.3% Westminster % % 3.0% Forest Heath % % 3.0% Colchester % % 7.0% Kensington & Chelsea % % -3.7% Bristol, City of UA % % 4.5% Newcastle Upon Tyne % % 3.8% Rushmoor % % 1.3% Brentwood % % 3.4% Portsmouth UA % % 2.8% York UA % % 4.1% These downward revisions show quite a range of different impacts on 2005 to 2010 population growth. Although the City of London has the second largest downward revision, its population growth is still very high and in fact remains the fastest growing authority in England and Wales. Indeed, nine out of the top 20 have post-revision population growth rates that are higher than the estimated population rate for England and Wales as a whole (ie 3.4 per cent). However, there are four LAs that have post-revision growth rates that are negative. These outliers are discussed in further detail in the next section. 20