Population and migration statistics transformation, Manchester case study: 2023

Manchester is a metropolitan area with a big population, largely characterised by its high proportion of students and high migration flows.

This brings challenges when estimating the population at a given time, meaning more timely and granular data are needed to provide the most accurate picture of Manchester's population and to best direct services to meet needs across the area. This article shows how we can use administrative data alongside a wider range of data sources to achieve this.

All admin-based statistics in this article are referenced to mid-year, and Census 2021 statistics are referenced to March 2021. This may lead to some differences in the comparisons. The exception to this is the admin-based population estimates (ABPEs) (excluding Figure 3), which are compared with the Census 2021-based mid-year estimates.

Population and Migration in Manchester

The size and structure of the population in Manchester is largely made up of young working-age individuals and students. These patterns are similar for admin-based population estimates (ABPEs) and census-based mid-year estimates (MYEs). Our ABPEs show that there were 549,600 people living in Manchester in 2021. This increased by 2.6% to 563,600 in 2022 (Figure 2). The population was 50.3% female and 49.7% male.

Figure 1: Admin-based population estimates (ABPE) data show the largest percentage of people living in Manchester were aged 20 to 29 years

Age structure of the population for mid-year estimates compared with ABPE, by sex, Manchester, 2021

Notes:

1. As Census 2021-based MYE is used as an input to the model, outputs are very similar to Census 2021-based MYE. There are small differences because the dynamic population model (DPM) balances the information available in population stocks and flows based on their respective measures of precision.

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Identifying movement of the population into and out of the area is also important for decision-makers to understand changing service needs, particularly around a special event such as the coronavirus (COVID-19) pandemic. Our ABPEs enabled us to see the change in population between 2021 (during various lockdowns) and 2022 (after lockdown) at least four months earlier than the current census-based system.

Figure 2: Manchester's population increased by 2.6% to 563,000 people between 2021 and 2022

Admin-based population estimates (ABPE) percentage change in population, local authorities in England and Wales

Notes:

1. City of London (plus 24%) and Isles of Scilly (plus 10%) have been omitted from the figure to show the distribution of all other areas more clearly across England and Wales.

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We are also able to understand more in local areas, such as Lower layer Super Output Areas (LSOA), by using administrative data on a regular basis to understand how the local populations are changing.

We have compared our ABPEs with Census 2021 estimates at LSOA level, with approximately 80% of LSOAs showing differences of within plus or minus 8% of the census estimates. There are greater differences between estimates than at local authority (LA) level in certain areas.

Our previous research shows these larger differences are often where there are communal establishments (CEs) with large, regularly changing populations concentrated in small areas, such as students in halls of residence or armed forces in military bases. These population groups are less likely to interact with services in a typical way and may not be captured at the same location as the census.

In addition to this, we see differences between census-based and admin-based estimates in areas with high levels of migration into and out of an area. This is because of differences in the reference period and the time taken to update administrative records following a move.

Figure 3: The largest difference in population estimates between ABPEs and Census 2021 were in LSOAs with communal establishments

Percentage difference in admin-based population estimates (ABPE) and Census 2021 estimates at Lower layer Super Output Areas (LSOA) level, Manchester, 2021

Notes:

1. Figures in this chart have used the Census 2021 estimates rather than our MYEs referenced in Figures 1 and 2. These have been used as a proxy since we are currently working on producing MYEs at local levels. For more information on this, please see our technical topic guide.

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Changes in Manchester's daytime population

Understanding who or what behaviours are causing these population changes further supports decision-making around directing services. For example, an area may need more medical services if the population increases significantly during the day.

Looking at the changes in Manchester's local area populations, we see certain areas experience higher population counts at certain points in the day, which we believe are accounted for by people travelling into and out of work or university.

• To view how Manchester's population changes over the day, please see Estimating the population by time of day.

• To view work-related travel to and from small areas in Manchester, please see Travel to work.

Population sub-groups and characteristics in Manchester

Beyond the size and structure of the population, we learn more about the make-up of the local areas and communities across Manchester by examining the characteristics of those who live there. This will aid us in further understanding where inequalities may exist across the local areas in order to identify where additional support or services may be required.

Manchester has a higher proportion of people identifying with each ethnic minority group (excluding "White" ethnic minorities when referring to ethnic minority group) in the admin-based ethnicity statistics (ABES) compared with the national figure ("White" accounts for 60.3% in Manchester, compared with the English national average of 82.9%).

The distribution of ABES aligns with Census 2021, with each ABES estimate shown to be within 4.0 percentage points of the census estimate (excluding "White" where the value falls to 2.2 percentage points). They are not the same because of differences in the way the data are collected, such as using different classifications and differences in self-reporting. The ABES estimate for the "White" ethnic group has the largest difference compared with the census, being 3.5 percentage points higher. We have analysed and produced evidence on this higher proportion of the "White" ethnic group in our Developing admin-based ethnicity statistics for England and Wales: 2020 article.

Figure 4: The ABES proportion of ethnic groups in Manchester is similar to Census 2021

Admin-based ethnicity statistics (ABES) and Census 2021 population by five-category ethnic group, Manchester, 2021 

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We can learn more about our population and their service needs through disaggregating by characteristics such as age and sex. For example, to better understand healthcare needs we can explore the differences between the types of ageing populations across our local areas.

Figure 5 shows the age breakdowns of different ethnic groups. We see more diversity across the younger age groups compared with the older age groups. For the "White" ethnic group the proportion of those aged under 16 is approximately 40%, compared with over 80% for those aged 65 and over. Understanding the make-up in local areas helps inform future health provisions for areas like Manchester.

These trends are similar to the overall Census 2021 ethnic group distribution and broadly comparable across the age groups.

Figure 5: Manchester’s younger age groups are typically more ethnically diverse than older age groups for both males and females

5a. Admin-based ethnicity statistics (ABES), “White” ethnic group by age and sex, Manchester, 2021

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5b. Admin-based ethnicity statistics (ABES), all other ethnic groups by age and sex, Manchester, 2021

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We can also learn about these differences at smaller local areas, including Lower layer Super Output Areas (LSOA). For more information on ethnic groups at LSOA level, please see our associated datasets, which include updated figures for 2021. Please see evidence of LSOA coverage by ABES in our previous Developing admin-based ethnicity statistics for England and Wales: 2020 article.

Using our admin-based income statistics (ABIS), we can form a more detailed picture of how the people of Manchester are living and understand inequality occurring at local levels.

Median occupied address net income is the income for people living at the same address, which we use as a proxy for households. In Manchester, median occupied address net income (£22,393) is lower than for England overall (£27,269), for reference tax year ending 2018.

By looking at the variation at LSOA level, we show that while this trend is true for most areas within Manchester, there are pockets where median occupied address net income is higher than for England. This is important for local planners and service providers to better target their services. There are some caveats to be considered when analysing these trends, for example, 3.3% of occupied addresses in Manchester have no recorded income on the administrative data. For more information, please see our technical topic guide.

Figure 6: Median occupied address net income varies across Manchester’s local areas with some affluent areas across the city

ABIS median occupied address net income (£), Manchester, tax year ending 2018

Notes:

1. Admin-based income statistics use the concept of occupied address to capture household income, grouping individuals who are recorded as living at the same address. 

2. Figures assume that income is shared evenly between all occupied address members. 

3. Net income is calculated by deducting Income Tax and National Insurance contributions (derived in accordance with HMRC guidelines) from gross income. 

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Our admin-based income by ethnicity statistics (ABIES) estimate the net income for individuals aged 16 years and over with income information identified by five-category ethnic group. With an ethnically diverse population and lower median occupied address income than the national average, we see similar trends reflected across individual income distributions, with lower individual incomes across all ethnic groups (Figure 7), although for different reference years. Further information on ABIES statistics, including explanations for the differences in the measures, can be found in our Developing subnational multivariate income by ethnicity statistics from administrative data article.

Figure 7: Income measures in the admin-based income by ethnicity statistics (ABIES) dataset for Manchester show variation between ethnic groups

The 10th percentile, median, and 90th percentile net income for individuals aged 16 years and over with income information identified by five-category ethnic group, Manchester, tax year ending 2018

Notes:

1. We are not yet able to determine how representative our analysis is of the total population and so these figures may not reflect the incomes of the underlying population and should be interpreted with caution. 

2. We were able to identify 75.5% of records with both income information and a stated ethnicity 

3. For more information on the categories included, see our technical topic guide.

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Housing, housing characteristics and living arrangements in Manchester

Looking beyond the individuals who make up our population, we have used administrative data to understand how people live together across local communities.

The census groups usual residents into households based on the self-reported use of shared facilities. Most residential addresses in England and Wales are used by a single household. In contrast, we report on occupied addresses because it is currently not possible to accurately identify multiple households at an address from administrative data alone. Addresses are most closely related to a self-contained dwelling definition. From the census, we estimate that this difference in definitions affects less than 1% of dwellings.

Our admin-based occupied address dataset (ABOAD) identified 199,400 occupied addresses in Manchester in 2021 compared with 214,700 households in Census 2021. The ABOAD counts occupied addresses while the census counts households, so multiple households living at the same address will be counted individually for the census. This is not the only factor contributing to the difference, for example we have undercount in our underlying dataset and the base population, and these factors are likely to vary across geographies. For more information, please see our technical topic guide.

Figure 8: There are more Census 2021 households in Manchester than occupied addresses in the admin-based occupied address dataset (ABOAD)

Number of occupied addresses in the ABOAD and households in Census 2021, Manchester, June 2021

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Occupied addresses with one or two persons living there were the most common among occupied addresses across Manchester in 2021. Census shows the same for households.

Figure 9: Most residential addresses in Manchester have one or two people living there

Size of occupied addresses in the ABOAD and households in Census 2021 by number of people living there, Manchester, June 2021

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To further understand people's living arrangements, we can use our admin-based housing stock version 1.0 (ABHS V1.0) statistics. This may help housing planners and policymakers better understand characteristics of the dwelling stock in their areas, and therefore better meet the future housing needs of residents. The ABHS currently provides the following housing characteristics:

• accommodation type

• number of bedrooms

• number of rooms

• number of bathrooms

• build period

Figure 8 shows that ABOAD counts fewer occupied addresses than census households. This is reflected in the ABHS. When comparing Valuation Office Agency (VOA) estimates of number of rooms with Census 2021 data, figures differ based on whether we analyse all residential or occupied residential addresses. In Figure 10, we see how the ABHS shows a similar distribution to the census, with most addresses in Manchester having between three and five rooms.

Figure 10: Dwellings in Manchester most commonly have three rooms

Distribution of Census 2021 households by number of rooms, alongside the distribution of residential addresses and occupied residential addresses in the ABHS V1.0, Manchester, 2021

Notes:

1. The admin based housing stock version 1.0 (ABHS V1.0) dataset counts addresses, while Census 2021 counts households, so multiple households living at the same address will be counted individually for the census. 

2. In contrast to previous censuses, Census 2021 did not ask a question on number of rooms, but it used linked administrative data. 

3. For more information on these different definitions see our technical topic guide.

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Knowing the age of dwellings in which residents are living allows us to further understand the features of our housing stock and plan for future need.

In Manchester, 53,285 dwellings were built before 1919, but only 45,400 were found as being occupied in 2021 according to the ABHS V1.0.

Figure 11: A large proportion of Manchester’s housing stock was built before 1919

Number of dwellings by Valuation Office Agency (VOA) build period for all addresses and occupied addresses in the ABHS V1.0, Manchester, June 2021

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Using the admin-based housing by ethnicity dataset version 2.0 (ABHED V2.0), we can extend our understanding of the living arrangements of different ethnic groups across Manchester. As an example, we have produced analysis on the accommodation type lived in by ethnic groups and the numbers of bedrooms in these dwellings.

In Manchester, there are differences in the types of accommodation occupied by different ethnic groups, which are also reflected in the number of bedrooms.

In Figure 12, we see terraced houses are the most common accommodation type for all ethnic groups (43.1%), with those in the "Black" ethnic group most likely to live in them. Individuals in the "Asian" ethnic group are less likely to live in purpose-built flats and more likely to live in semi-detached houses than other ethnic groups.

Figure 12: Terraced houses are the most common VOA accommodation type for all ethnic groups in Manchester

Admin-based housing by ethnicity dataset version 2.0 (ABHED V2.0) VOA accommodation type (Census 2021 definition) by ethnic group, Manchester, 2021

Notes:

1. Data are by individual and not by addresses, as used in housing figures in the above housing section. 

2. Valuation Office Agency (VOA) accommodation type is a derived variable designed to align with the Census 2021 definition; for more information see our technical topic guide.  

3. Figures have not been adjusted to account for differences in age structure or household size by ethnic group within the population.  

4. Figures include supressed and rounded values, so some categories appear under or over 100%.

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While the most common number of bedrooms for all ethnic groups is three, those in the "Asian" ethnic group are more likely than all other ethnic groups to live in dwellings with four or more bedrooms (see Figure 13).

Figure 13: Individuals in the “Asian” ethnic group are most likely to live in dwellings with four or more bedrooms compared with all other ethnic groups

ABHED (V2.0) VOA number of bedrooms by ethnic group, Manchester, 2021

Notes:

1. Data represent individuals rather than addresses, as was used in the above housing section. 

2. There are differences in definition between the number of bedrooms for Census 2021 and the Valuation Office Agency (VOA) data used in the admin-based housing by ethnicity dataset; for more information see our technical topic guide.  

3. Figures have not been adjusted to account for differences in age structure or household size by ethnic group within the population.  

4. Figures include supressed and rounded values, so some categories appear under or over 100%.

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Beyond the population living in private households, we can learn more about the characteristics of the population living in communal establishments (CEs). CEs are places with full or part-time supervision providing accommodation. These groups are challenging to capture in our population, so work has started to understand more about who is living there. With more frequently updated figures, we can capture how the population living in CEs changes over time and the impact this has on the service provision for local areas.

The admin-based communal establishment dataset (ABCED) shows that the total population living in CEs in Manchester was 21,325, compared with 21,798 on the census. Of those found in CEs on administrative data, 84.5% lived in halls of residence.

Through disaggregating by age and sex, we see who makes up the population of residents in CEs across Manchester.

Figure 14: The most common age group of communal establishment residents in Manchester was those aged 16 to 24 years for both males and females

Admin-based communal establishment data (ABCED) communal establishment residents by sex and banded age groups, Manchester, 2021

Notes:

1. The ABCED has a different reference period compared with the data used in the occupied address dataset, so they are not directly comparable. 

2. Figures are not directly comparable to official Higher Education Statistics Agency (HESA) halls of residence figures as the base population only includes usual residents, while HESA includes all who are registered. 

3. These figures are not comparable with official Ministry of Justice data on residents in prison. 

4. The ABCED includes raw figures and has not had additional estimation methods applied, unlike the official Census 2021 estimates. 

5. Percentages have been calculated for the whole population, so each individual sex will not total 100%; this differs from previously published figures which are therefore not comparable. 

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The analysis presented in this article shows how our admin-based statistics can support our understanding of the diverse and changing needs of the local communities across Manchester. This demonstrates their potential and is just a subset of what users can expect from our future population and social statistics system.

• View the administrative data story of another local area.

• For more information on the methodology behind the administrative data collections referenced previously, please see our technical topic guide.

To find out more about our progress towards a transformed population and migration statistics system, please see our research overview.