Statistics are vital: An interview with Sarah Caul MBE

'Statistics Are Vital’ is a joint campaign by the Royal Statistical Society and Significance magazine, celebrating the work of statisticians during the Covid-19 pandemic. 

The RSS spoke to Sarah Caul MBE, head of mortality analysis at the Office for National Statistics.


‘With statistics, so much goes into one number – the amount of coders, the data managers, the analysts, the people who write the bulletins – so much goes into the process.’

How have you been involved in the response to Covid?
As head of mortality analysis at ONS, my job is to investigate the number of deaths registered in England and Wales. When the pandemic started, we expanded a lot of our work to include the number of Covid deaths on a weekly basis and some ad hoc releases investigating the different aspects of mortality and Covid.

When did you realise Covid was going to have a massive impact on both your work and home life?
Because other countries were affected before we were, early on we were looking at how we could scale up the releases we already had in case we did have a lot of deaths. I remember our week 11 release in March 2020 reported five Covid deaths, the next week we had 103. That was the point I realised that it was going to impact us for quite a while. Also, one of the people I lived with at the time was an intensive care nurse looking after people with Covid, so I was aware the situation was bad in hospitals and I was seeing this in the statistics as well. There wasn’t much of an escape from Covid in my house at the time.

I purposely worked quite a lot. I live with depression and as the world was locking down my answer was to throw myself into the job which I love. During the first few months I was working quite intensely,  including over the weekends ahead of the weekly deaths bulletin on the Monday. While our managers would have found a solution if we weren’t able to put the extra hours in, everyone was keen to do it. While previously we had a coding system which automatically codes the cause of death from the death certificate, when Covid came in we had no automated information for it so it had to go to manual coders. This job requires a very specific skill set and training so we couldn’t just recruit more people. This small team worked staggeringly hard to code the death certificates as the death toll increased.

As things started to ease and the number of deaths stabilised we were able to come up with solutions and automate things in preparation for the second wave.  We managed to get more staff in and rationalised some of our releases. While it did get incredibly busy at this point, we were better prepared to combat the issue so there wasn’t such a need to work as many long days and weekends. 

How did you and the team stay motivated?
I’m very enthusiastic about my job, which I know sounds morbid as I work on mortality statistics, but it’s one of the things that has got me through the pandemic. I love being a statistician and I’ve worked in different areas, but mortality is where my heart is. As a statistician, I couldn’t necessarily help at a hospital but I could give evidence of, for example, this group of people being more at risk of dying from Covid over an another, so it was my way of helping to hopefully reduce the number of deaths.

I think my enthusiasm and love for my job motivates the team. I also put a lot of focus on staff wellbeing. Because I am open about my depression, I focus a lot on the importance of mental health which became even more important during the pandemic. Especially working remotely, it’s more difficult to check people are actually ok. This involved organising team events and building relationships as we had many new staff who hadn’t had the chance to meet their team members in person.

How did you cope with the sudden interest in your work?
I mostly loved it. In the first wave my mobile number was on all mortality releases and my phone was constantly ringing. I was used to phone calls from journalists, but this time it was everyone and anyone – members of the public really wanting to understand the numbers. When it moved to Twitter it made it easier, as I could plan out threads with answers to commonly asked questions, but it can be really hard to answer a question in a limited number of characters. You don’t get the same immediate feedback from people as you do when speaking on the phone. Most people were really grateful that you responded to them, but some, of course, weren’t.

What’s the greatest challenge you’ve faced?
Staff wellbeing. While with the work itself there were straightforward steps you could take to resolve any issues, as the team got bigger and we were working remotely I worried about how everyone was doing. You knew people were facing their own personal difficulties living through the pandemic - everyone was locked down and not seeing anyone, and you didn’t know how this was affecting different people

What aspect of your work are you most proud of?
I’m proud of the sheer amount of work we got out and the efforts we made to explain all the different stats. We did a lot of explainers, for example, on the difference between our numbers and Public Health England’s and Public Health Wales’. We also managed to link the 2011 Census to death records to have a view on Covid and ethnicity. I am proud of how well we worked together and overcame the challenge – there was so many statistics and we had to get it right. I should also mention my MBE for my work at ONS – I’m immensely proud of that.

What were the positives you took from this difficult period?
The people I worked with were amazing. With statistics, so much goes into one number – the amount of coders, the data managers, the analysts, the people who write the bulletins  – so much goes into the process. While some of the bulletins might just have had my name on them, without all these people we couldn’t have published them.

What’s likely to change in your role as we move out of the pandemic? 
I think some of my role will stay the same. We do a lot more monitoring work now and I think some of this will continue, for example, with monthly releases which we didn’t do pre-pandemic. We still have work to do on the long-term effects, including on mortality displacement. We need to look at what data we’re missing and then we’ll look to what we should move on to.

How would you summarise the contributions made by statistics and statisticians in tackling this global health emergency? 
I think it’s been amazing, which I know sounds cheesy. I can’t believe everything everyone’s done, and so quickly. The PHE dashboard, for example has got so much on it. Everyone’s worked together really well. During the pandemic I had a fortnightly meeting with different producers of mortality stats, and while everyone was so busy they still attended so we could ensure we knew what others were doing and our work was consistent. Some people don’t understand how much goes into it, but when you’re on this side of statistics it’s pretty impressive. Everyone should be very proud of themselves.
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