Surveys are ubiquitous nowadays but (with occasional exceptions such as the 2015 election polling) few people other than specialists tend to get excited by them. The fact is, though, choosing a representative sample of people, contacting them, questioning and measuring them, then analyzing the results, is a difficult logistical challenge. And there is a class of survey that represents an even higher level of difficulty – cohort studies.
In a cohort study, a sample of people who share a common characteristic (such as a date of birth) are recruited and investigated. The cohort is then repeatedly re-investigated over a period of time. The challenge isn’t just to recruit the cohort in the first place, but to keep track of them over years and decades.
When James Douglas, a 31 year old doctor and researcher, set out to collect details about all the babies born in the week of 3-9 March 1946, he didn’t know he was beginning a cohort study. The challenge was enormous enough to begin with, as health visitors across the country were enlisted to collect details of all the babies born that week (they managed to visit 13,687). But as Helen Pearson shows, that initial cohort was laboriously re-traced a few years later and then repeatedly re-contacted as its members grew from babies, into children, adolescents and adults.
Now on the threshold of old age and still regularly surveyed, the 1946 cohort has been joined by other cohorts from 1958, 1970, 1991 and 2000. These studies have produced over 5000 journal articles and 40 books covering the social sciences, medicine, epidemiology, genetics and other fields. What they offer is a kind of ‘natural experiment’; by tracking cohorts over time and comparing them to other cohorts, researchers can track the impact of social and political changes on different kinds of people.
Some of the findings concern health, showing up the harmful long-term effects of smoking and obesity for example. One theme, though, dominates: inequality. Not only has inequality been remarkably persistent since 1946, but its effects echo through the decades. Inequalities in health, education and many other measures often stay with the poorest members of the cohort for life.
The Life Project is in many ways a very British story. The cohort studies are unmatched globally in their depth and scope and have inspired imitators in many other countries. Yet there never was a master plan to initiate them in the first place. Although funded by and used by government, it has been a constant struggle to set up and maintain each cohort study. As in other areas, Britain came to lead the world accidentally, through constant improvisation, in the face of institutional muddle.
This absorbing book is nothing if not a tribute to Helen Pearson’s skill as a writer. While The Life Project isn’t a thriller, the book does wring plenty of drama out of the endless politicking and financial brinkmanship that has kept the cohorts on the road. Far from grey bureaucrats and number-crunchers, many of those who founded and maintained the cohorts were appealingly idiosyncratic, and their single-minded passion drove some close to a breakdown.
Pearson doesn’t neglect the research subjects themselves (over 70,000 of them by now). The book is sprinkled with pen portraits of cohort members whose everyday struggles bring the statistics alive. For members of the 1946 cohort in particular, there is a certain amount of pride in being involved in such a ground-breaking study – there are meet-ups, birthday parties and even a Facebook group.
However, the book ends on a – hurriedly rewritten – downbeat note in the final chapter. A new cohort was due to be initiated this year, but after several millions pounds worth of preparatory work, funding was pulled by the Economic and Social Research Council towards the end of 2015. While the reasons for this are complex, it’s hard not to avoid comparing the fate of the 1946 and putative 2016 cohorts. Both were planned in austere times, but it’s worth pondering why the post-war generation was better served than the one that is now being born.
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