It was great to listen to Ben Goldacre’s programme ‘From Cradle to Grave’ on Radio 4, which rightly celebrated longitudinal research’s amazing contribution to our understanding of how the environment, lifestyle choices and social circumstances impact on our health. But it's not just the medical sciences that deploy longitudinal research to such great effect, these studies are also a powerful tool used by the social sciences.
In fact, those of us who work in the social sciences have been following the lives of individuals ‘from cradle to grave’ for a really long time. (No pun intended, I promise!) The British social science community has reason to be proud of its longitudinal legacy, the Radio 4 programme mentioned Britain’s longest running birth cohort study – the 1946 Birth Cohort
– but there’s also the National Child Development Study
, the British Cohort Study 1970
, and more recently, the Millennium Cohort Study
. These fantastic studies are run by our colleagues at the Centre for Longitudinal Studies and have yielded some fascinating insights, including the discovery that breast-feeding is associated with reduced risk of heart disease, particularly pertinent at the moment as last week was National Breastfeeding Week.
Here at NatCen, my colleagues and I are lucky enough to work on flagship longitudinal studies, like Understanding Society and the English Longitudinal Study of Ageing. Of course, these studies bring their own unique challenges as well as practical difficulties, such as how to visit up to 40,000 households each year as we do for Understanding Society. But there are also key methodological nuts to crack in order that the data produced from these studies can be reliable and representative of the broader population.
Ben Goldacre discussed some of these challenges in his programme, specifically, the problem of collecting data retrospectively. As many of you reading this blog will know, interviews on longitudinal studies are the main way of finding out what’s happened to a participant since the previous research encounter. So it’s really important that whatever method is used to elicit information from them can be relied upon to consistently trigger people’s memories of key facts and experiences. How to tackle this issue of recall is something that longitudinal researchers like me spend a lot of time thinking about. One innovative solution we’ve come up with at NatCen is to develop life history calendars. These calendars give people the flexibility to recall significant events first – such as a child’s birthday - and then use that event to help trigger memories of what else was happening at the same time. By this means we gradually build up a picture of people’s lives from over 50 years ago. These life history calendars were first developed for use on the English Longitudinal Study of Ageing, and have been so successful that they’ve since been used on other longitudinal studies, such as the Survey of Health, Ageing and Retirement in Europe and the Health and Retirement Study in the US.
I’ve chosen to work in longitudinal research because there’s huge satisfaction to be had in finding out how an individual’s early experiences determine their outcomes in later life. These rewards are reflected on in Paul Bradshaw’s blog about the birth cohort study Growing up in Scotland, which is well worth a read. I think this is a really interesting time for research conducted over the life course, as these studies will help us understand the impacts of big societal changes on people’s lives. I’m thinking here not only of the Big Society, but other important changes, the impact of the economic downturn or the rise in university tuition fees immediately spring to mind. Our future understanding of how these changes play out in society really depends on how much we decide to invest in longitudinal studies now.