Sometimes the data doesn’t fit our expectations. Take this question:

Who’s healthier, migrants or people born in the UK?

To find out, I turned to data from the 2021 UK Census. It’s a huge survey that runs every ten years, capturing a detailed picture of the population; everything from health and ethnicity to migration and employment. It’s the kind of dataset that helps us understand how society is changing and shapes the policies that follow. To explore it efficiently, I used an AI-driven analytics platform; Point Sigma, which helped me quickly browse and visualize many different patterns.

So, what did I find?

Bad Health by Age Group: UK-Born vs. Non-UK-Born

Among all working age groups, migrants report better health than UK-born individuals. It wasn’t what I expected. It made me question my assumptions about health, access to care, and the impact of socio-economic disadvantage. Wouldn’t migrants, facing more barriers, report worse health?

But after thinking about it, it started to make sense. Can you see why?

Migration is a selective process. Healthier, more active people are more likely to move countries. Those facing serious health issues are less likely to uproot themselves. That selection effect helps explain why migrants often report better health; at least in the earlier stages of life in a new country.

Digging Deeper: Understanding the Data

Still, the graph raised more questions than it answered. Even if this pattern makes sense, does it hold true across all groups?

What about over time? By the time people reach 55 to 64, the health gap between migrants and UK-born individuals pretty much disappears. Does the health ‘boost’ wear off the longer someone lives in the UK? Or maybe socio-economic standing starts to play a bigger role as time goes on?

These questions pushed me to dig deeper. Since health usually declines with age, let’s focus on the 35 to 44 age group; a good snapshot of working-age adults that lines up with broader trends. I looked at both good and bad health, but because they showed the same story, I focused on bad health as the clearest measure. I also checked for differences between men and women but found no meaningful changes so I combined them for simplicity.

With that in place, I wanted to know: does where you come from make a difference? Let's take a closer look.

Bad Health by Region of Birth: Age 35-44

In the 35-44 age range (and all working age groups except 55-64), migrants from every region report better health than UK-born individuals.

Some patterns stick around across ages: for example, migrants from Asia usually report worse health than others, while those from Oceania often come out healthier. Although it’s worth remembering that some migrant communities have been here much longer than others; that could be a big part of why we see these differences. So, it makes you wonder: how much does the time spent living in the UK affect how healthy people are?

Bad Health by Year of Migration: Age 35-44

When you look more closely at working-age people and when they arrived, a clear pattern starts to emerge: Long-term residents report significantly poorer health than recent arrivals, even though they’re the same age. This seems to hold true no matter where people come from. In fact, for regions like the Middle East and Asia, people who’ve lived here longer often report worse health than those born in the UK.

This pattern continues into older working-age groups, but the differences between regions become clearer. For people from the Middle East and Asia, the gap between recent and long-term migrants narrows with age. In contrast, migrants from Africa, the Americas, and the Caribbean show a much sharper drop in health among those who’ve been here longer.

These regional differences and changes over time raise questions about the role of socio-economic factors. Could they reflect how integration, opportunities, or barriers affect people as time goes by?

Bad Health by Job Category: Age 35-44, Region: Asia vs UK

It is clear that people in lower-paid or routine jobs tend to have worse health.

But here’s the interesting part: recent migrants in the same jobs often report better health than those who’ve been here longer. For example, migrants from the Middle East and Asia working routine jobs who arrived recently have health comparable to UK-born people in higher-level roles.

So why does health seem to decline the longer migrants live here? And why are the biggest differences in routine jobs? Could certain types of jobs carry specific health risks?

What starts as a simple observation quickly turns into a complex web of overlapping influences; where job type, time in the UK, and migration all come together to shape health.

Reflection: What does this teach us about working with data?

Data surprises us even when it eventually makes sense. The best lessons don’t come from what we expect but from the questions surprises make us ask. When the Census showed migrants reporting better health than people born in the UK, it challenged common ideas about disadvantage and healthcare. Sure, migration’s selective nature helps explain it, but curiosity pushes us to look deeper instead of settling for easy answers.

Good analysis is about depth, not just confirmation. Digging into how migration, time, and socio-economic factors connect reveals richer stories beneath the surface. Surprising results aren’t the end. They’re a chance to ask better questions.

How can we shift our thinking to see surprises as starting points, not conclusions?

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Office for National Statistics. (2024). 2021 Census: Safeguarded Individual Microdata Sample at Grouped Local Authority Level (England and Wales). [data collection]. UK Data Service. SN: 9155, DOI: http://doi.org/10.5255/UKDA-SN-9155-1. No safeguarded data was shared; only aggregate numbers were used for plotting.