Is longitudinal research the best response to the ‘post-truth’ order?

In God we trust, all others must bring data.

Longitudinal studies are an irreplaceable resource for understanding trajectories, transitions and shocks over time. Undeniably, the UK leads the world in tracking the life course of its citizens through longitudinal research. The British birth cohorts - a treasure trove of data covering five generations of children - now comprise the longest running studies of the way human beings develop over time, anywhere. With so much invested in research of the life course, UK data stands at a cross-roads, facing important questions for the future of longitudinal research. It also provides important lessons for other countries considering large investments in this extremely valuable form of research. The urgency for making greater use of longitudinal research has arguably never been greater. The UK is undergoing vigorous change, due to technological innovations, financial and economic crises, demographic and political shifts. Longitudinal studies remain the single best tool to understand how society is affected by the powerful forces unleashed by these changes. The bizarre new climate of post-truth populism adds an exclamation point to the urgency for quality data and rigorous research to underpin policy. Recently, experts from across the UK and abroad came together at Nuffield College, Oxford, to share their experiences of longitudinal data design, collection and use. The meeting was convened by the UK's Economic and Social Research Council (ESRC) to inform their investments in longitudinal research. Over the course of ESRC's 50 year existence it has allocated a significant volume of funds to longitudinal data gathering, and currently invests up to 10% of its total budget in longitudinal research. As well as a series of birth cohort studies starting in 1958, ESRC also funds the world's biggest household panel survey, Understanding Society, a number of Census-linked Longitudinal Studies, and the Cohort and Longitudinal Studies Enhancement Resources (CLOSER).  Keep calm and focus on data linkage The workshop focused on future needs and how they can be met. Experts discussed how to relate longitudinal data investments with other data, such as cross-sectional or administrative data. Over two million Britons have enrolled in one longitudinal study or another. One popular suggestion was to create a 'spine' that longitudinal data can be linked to, or to create direct linkages among various longitudinal data resources. Restructuring the current set of studies into a broad based resource has financial, technical and political challenges. Linking data sets has large infrastructure costs which need to be weighed against the potential benefits. The upcoming Digital Economy Bill, with its implications for data management, civil registration and privacy, will bear on the success of data linkage. Here, the UK could learn from other countries. The Nordics have a long history of collecting data on vital events, migration, disease and social conditions. For example, the Danish national registers link different data domains through a unique personal identification number. High-quality data made available through a national data repository can be accessed for the whole population over long periods of time. ESRC has made progress in the area of data linkage by funding the Administrative Data Research Network: a network of centres that negotiate access to administrative data.  Technology - all that glitters is not gold. Technology could be a crucial amplifier for longitudinal researchers. Digital devices can provide ways to increase retention, improve quality and decrease costs of data collection. These technologies can have profound effects. They can expand the way we think about survey data collection and increase the ways we can interact with survey respondents. However, to harness the full potential of technology for longitudinal research, more study is needed, including better understanding the relationships between online and offline behaviours. Data protection - in particular regarding ethics and privacy - warrants much closer consideration. Beyond British borders Longitudinal research is central to the promise of a 'data revolution' to accelerate the achievement of development goals. It is also key to tracking the contributions toward improving human lives. The UK plays a leading role in promoting the international development agenda; hence, it can and should lead efforts to promote use of longitudinal research to inform international development programmes. Impact evaluations, including randomised control trials and quasi-experimental studies, are responding to the call for 'what works' in low- and middle-income settings. These studies collect data over repeated rounds, though much of it remains under-analysed, and poorly linked to other data. How these can be harnessed beyond their narrow purpose remains an important question. Significant investment will be required to close capacity gaps in low income settings in order to bring data collection up to international standards. The discussion is timely: RCUK has recently pledged £1.5 billion over the next five years under its Global Challenges Research Fund. This could spearhead data initiatives in the developing world, and contribute to better measurement of the Sustainable Development Goals. The Global Longitudinal Research Initiative (GLORI) launched by UNICEF Innocenti could provide a valuable contribution to North-South dialogue on longitudinal research. In addition to exploring data linkage and technologies, concurrent investments in data governance, interdisciplinary research, user and producer capacity, as well as in oft forgotten science journalism, are also critical. Many are watching to see how UK investments will respond to the challenges of a new world order. The UK should not underestimate the crucial role it plays globally in bolstering good science and research across the life course. More information on the ESRC Longitudinal Studies Review 2017 can be accessed here. Prerna Banati s Chief of Programme and Planning at  the UNICEF Office of Research - Innocenti.  Explore the  UNICEF Innocenti research catalogue  for new publications. Follow UNICEF  Innocenti on Twitter  and sign up for e-newsletters on any page of the UNICEF  Innocenti website.