Bridging the data gap for ethnic group and religion

A group of young people in London

Our population is ever-changing and having an up-to-date picture of the ethnic and religious diversity of England and Wales is crucial for policy makers and providers of public services. Previously, the official estimates of the population by ethnic group and religion were from the 2011 Census. Ahead of Census 2021 results, Sarah Coates explains how the ONS has responded to the on-going need for data on these areas by producing new, experimental statistics.

There is a strong user need for timely data by ethnic group and religion. This is especially significant now, as the coronavirus (COVID-19) pandemic has highlighted the urgent need to improve the evidence base around ethnicity and health. Previously, census data were our latest official estimates by ethnic group and religion but, as time goes by, the population estimates will not reflect change since census day.

We have listened to user feedback from our previous research and, using the three-year-pooled Annual Population Survey data in combination with 2011 Census data and the Mid-Year Population Estimates, we have now provided 2019 population estimates for 18 ethnic groups and 8 religions by age, sex, country and region for England and Wales as experimental statistics.

Because our results are produced using survey data, they are estimates and not precise figures. As the number of people in the sample gets smaller, the variability of the estimates that can be made from that sample gets larger.  In addition, the survey data from which our estimates are based are collected either face-to-face or telephone compared to self-completion of the census, this could influence how an individual reports their ethnicity.

Therefore, despite some interesting findings, it is not possible to fully quantify how much of the change between the 2011 Census and our experimental estimates is a reflection of true change or differences caused by data collection.

In 2019, the most common ethnic group in England and Wales was White (84.8%), decreasing by 1.2 percentage points since the 2011 Census. The next biggest change from 2011 was in the ‘Other ethnic group’ which increased by 0.9 percentage points, at the 5 ethnic groups level.

As part of the White ethnic group, an estimated 78.4% of the population in England and Wales identified their ethnic group as White British in 2019, a decrease of just over 2 percentage points since the 2011 Census; Other White increased by nearly 1.5 percentage points to an estimated 5.8%.

When looking at religion estimates, we can see that around half (51.0%) of the population reported their religion as Christian in England and Wales, a decrease of nearly 8.3 percentage points since the 2011 Census. Meanwhile, No religion (which has been combined with Not stated for the purposes of these analysis), the second most common response, has increased from 32.3% to 38.4% in 2019.

Our new experimental statistics also look at regional changes and differences in the age breakdowns across the 18 ethnic groups and 8 religions.

How should this data be used

Our Review of the current evidence base for population estimates by ethnic group  considers the strengths and limitations of the estimates produced by the ONS, as well as making recommendations as to which estimates to use when.

We outline that census data remain our ‘gold standard’ source for population estimates by ethnic group in England and Wales and are recommended to be used for analysis, especially when considering more detailed population groups than the 18 ethnic groups by age (10-year age bands), sex and region.

Data from Census 2021, out next year, will provide a detailed and accurate picture of the population of England and Wales by ethnic group, but these estimates will not reflect change since Census day.

If Population estimates by ethnic group and religion in England and Wales: 2019 meet user requirements and are deemed reliable when compared to 2021 census data, they will be produced annually.

The estimates are at the country and region level, by age (10-year age bands), sex and age and sex combined. A previous research report on population estimates by ethnic group and religion found that it was not possible to produce these estimates at a local authority and unitary authority level as sample sizes were not large enough.

A strength of our new method, which combines data from the three-year-pooled Annual Population Survey (APS), Mid-Year Population Estimates (MYEs) and the 2011 Census, is that it accounts for the differing ethnic distributions in the household and communal establishment population.

The methodology is, however, limited by the assumption that the proportions of the population groups within England and Wales living in households and communal establishments remain unchanged since the 2011 Census. The validity of this assumption is reduced by several factors such as population change. For example, the ageing population may be resulting in increased demand for communal living.

The combined method also assumes that the ethnic distribution of the communal establishment population will have changed since the 2011 Census in a similar way to the household population.

This assumption would likely impact areas which have seen rapid population change, therefore the decision to not produce these estimates at a lower-level geography limits the potential impact of the estimates.

What next?

Following the release of Census 2021 data, we will publish a comparison of the experimental statistics and the census data to assess the accuracy of the ‘combined method’ methodology used to produce the estimates. We also plan to update our methodology to incorporate Census 2021 proportions for the communal establishment population.

There are many possible uses of the new annual estimates, including the potential for them to be used within health analysis as population denominators for estimating rates of disease prevalence, mortality, and life expectancy by ethnic group.

This is especially significant now, as the COVID-19 pandemic has highlighted the urgent need to improve the evidence base around ethnicity and health. Currently, the data sources used to produce National Statistics outputs on mortality for England and Wales do not include ethnicity information; therefore, the ONS has developed experimental statistics using ethnicity information from the 2011 Census and a cohort design for mortality estimates by ethnic group.

These new population estimates by ethnic group, if combined with sufficiently good quality estimates of deaths by ethnicity, will enable important triangulation of data sources with scope to publish additional experimental statistics on mortality by ethnic group in the future.

If you have any feedback on our new experimental statistics, contact EILR@ons.gov.uk

Sarah Coates

Sarah Coates is the ONS’ topic lead for Ethnicity, Identity, Language and Religion