Skip to content

How big is this number? Learning from Cities Outlook on how to think about data

arrow down

Looking at data is essential to understand local economies.

But how best to do this? This year’s Cities Outlook  from Centre for Cities – one of our two host organisations – provides an example.  Cities Outlook compares 63 cities and towns with a daytime population of over 135,000, so although this won’t cover all places across the UK, the ideas around use of data remain the same.

Comparison – how big is this number?

We stress in our course, Making use of evidence that it’s critical to ask ‘how big is this number’? Comparisons are one way to do that. But choosing the right comparators can be difficult. In the Centre for Cities report there are generally three comparisons at work—ranking all 63 cities and towns, comparing Greater South East vs elsewhere in the UK, and comparing back to how each place performed in 2010.

Comparing these same 63 towns and cities is something Centre for Cities has consistently done for years and is undoubtedly helpful for policy makers in those places.

The Greater South East vs the rest of the UK is a common comparison—there are policy reasons such as concerns about Levelling Up, as well as trends in the data, which explains its popularity. This can be particularly helpful when trying to push for policy change nationally if there is a stark difference. Another popular option is to compare local statistics with UK or England excluding London, which removes London as an outlier on many indicators. This will not be appropriate for every place, or for every indicator.

These comparisons can all help to put the figures from a local economy into context—to really understand whether the figure for a specific place is a big number. Job growth lower than places similar to your local authority, may be reason to look at ways to support businesses. But if part of the reason for this is that your area has an ageing population, so there are fewer people of working age than those other local authorities, the policy response may be different.

Choosing your indicators – which data matters?

It’s not only choosing the right comparators within an indicator that matters, the mix of indicators matters too.

Cities Outlook, starts with three different indicators—change in jobs, productivity and disposable income since 2010. Across all the 63 cities and towns, all but two saw jobs growth and a majority had growth higher than the 12 years prior to 2010.

However, the two other indicators—productivity and disposable income—show a different picture. Only six cities and towns, all in the Greater South East, had growth higher than 1998-2010, and 18 have negative growth. On disposable incomes, only London saw growth higher than 1998-2010.

It’s important to consider multiple indicators when measuring local growth to build a more complete picture.

Level or growth?

In most cases, Cities Outlook leads with charts that show growth—the change over time. This helps tell a story of change since 2010 and makes it easier to compare 63 towns and cities with a wide variation in the starting positions. Seeing growth over time can be useful, particularly when trying to identify trends, or compare it to specific changes in the local economy. 

While growth can be a useful measure, levels – the value at a particular point in time (for example output per hour worked) – matter too. Fast growth from a low base won’t necessarily be better than low growth from a high base.

For example, in terms of productivity growth, Huddersfield and Doncaster are in the top 15 of output per hour, but in the bottom 15 in output per hour when looking at the level of productivity in the Cities Outlook report.   

Deciding whether to report on growth, levels, or both can influence the policy decisions that are made.

Learning from others

These are just a few takeaways on how we can present and think about data. Looking at how the data is visualised and ordered is useful too. In this report, and in others, consider the way data is presented. Is it easy to read? Are the key points clear from looking at it? Does the order work if there are many indicators included? 

Over the next few months, we’ll be working on a new set of resources and tools to help those in local government better understand the data that is available through CfC, ONS and others.