May 21 2014
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Conferences, News, Publications

Attending Alife 14 in New York

I’m pleased to say that another recent paper, this one titled Advancing Social Simulation: Lessons from Demography, has been accepted to the Alife 14 conference in New York.  I’ll be giving an oral presentation on this work, which was a joint project with Jakub Bijak, Daniel Courgeau and Robert Franck.  This is an early version of a rather complicated set of ideas that we hope to publish in a larger journal paper sometime down the line.

Abstract follows:

Previous work has proposed that computational modelling of social systems is composed of two primary streams of research: systems sociology, which is focused on the generation of social theory; and social simulation, which focuses on the study of real-world social systems. Here we argue that the social simulation stream stands to benefit from recent methodological and theoretical advances in demography. Demography has long been an empirically focused discipline focused primarily on mathematical modelling; however, agent-based simulation have proven influential of late as demographers seek to link individual-level behaviours to macro-level
patterns. Here we characterise this shift as a move toward system-based modelling, a paradigm in which the scientific object of interest is neither the individual nor the population, but rather the interactions between them. We first describe the four successive paradigms of demography: the period, cohort, event-history and multilevel perspectives. Then we examine how system-based modelling can assist demographers with several major challenges: overcoming complexity in social research; reducing uncertainty; and enhancing theoretical foundations. We propose that this new paradigm can enhance the broader study of populations via social simulation.

I’ll upload the full paper once the final corrected version is done and submitted.  The conference proceedings will be open-access in MIT Press.

Hope to see some of you in NYC!

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May 12 2014
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News

Giving a talk at the Oxford Institute of Population Ageing

If anyone happens to be in Oxford this Wednesday, I’ll be giving a talk at the Oxford Institute of Population Ageing from 12.30PM – 2PM which is titled “Agent-Based Models in Demography: Modelling the Ageing UK Population”.  Here’s the abstract:

Agent-based models are becoming increasingly popular in demography, due to their potential for studying the links between micro-level behaviour and macro-level population change.  In this talk I will discuss the implementation of two agent-based models as part of the EPSRC-funded Care Life Cycle Project, which is focused on studying the impact of the ageing of the UK population on the supply and demand of health and social care.  As well as presenting these models and their results, I will also outline the underlying motivations behind our choice of methodology, and describe some of the conceptual and practical challenges that we have encountered while constructing these models.

I’ve set myself a big task here to get through all this in 45 minutes, but I think I can just about make it!  Do come along and join the discussion if you have a chance.

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Mar 28 2014
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Conferences, News, Publications

Article forthcoming in Revue Quetelet

As you may have seen in a previous post I was involved in two submissions to the recent Chaire Quetelet Seminar at the Université catholique de Louvain.  Our paper titled “Are the four Baconian Idols still alive in Demography?” has now been accepted to the Revue Quetelet journal after passing peer review, and should appear soon once we do some minor revisions.

Unfortunately I was unable to attend the actual seminar at the time due to UK visa problems, but I heard from my colleagues that it was a very successful and stimulating event.  I should note that all three of my co-authors speak French, so I suspect the French-language portions of the seminar would have been much more difficult for me, but still I trust their feedback 🙂

I’m very pleased to be involved in such stimulating papers and to be publishing for the first time in a bilingual English/French journal!  Please do click the paper title to read our submitted version for now, and look forward to our revised version which will then appear in Revue Quetelet later this year.

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Mar 28 2014
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News, Publications

Paper published in Demographic Research

Just had another publication pop up online!  This one is an examination of paradigm change in demography and an argument for developing a new sub-field around the history of population science.  I’m pleased to say this one is also in Demographic Research, an open-access journal with some of the most cheerful and helpful editors around.  This paper’s called Quantifying paradigm change in demography and was written by Jakub Bijak, Daniel Courgeau, myself, and Robert Franck.

Our paper for Population and Development Review is still being looked at, but with luck we may hear about it soon.  In the meantime take a look at this one, and do support Demographic Research if you publish in this area — we should all be supporting high-quality open-access journals as much as we can.

Here’s the abstract:

Background: Demography is a uniquely empirical research area amongst the social sciences. We posit that the same principle of empiricism should be applied to studies of the population sciences as a discipline, contributing to greater self-awareness amongst its practitioners.

Objective: The paper aims to include measurable data in the study of changes in selected demographic paradigms and perspectives.

Methods: The presented analysis is descriptive and is based on a series of simple measures obtained from the free online tool Google Books Ngram Viewer, which includes frequencies of word groupings (n-grams) in different collections of books digitised by Google.

Results: The tentative findings corroborate the shifts in the demographic paradigms identified in the literature — from cross-sectional, through longitudinal, to event-history and multilevel approaches.

Conclusions: These findings identify a promising area of enquiry into the development of demography as a social science discipline. We postulate that more detailed enquiries in this area in the future could lead to establishing History of Population Thought as a new sub-discipline within population sciences.

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Feb 11 2014
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News, Publications

Paper Submitted to Population and Development Review

Another collaborative paper is now under review — this one a lengthy discussion of the future of demography called “From the past to the future of demography”.  There were four of us on this one: myself, Jakub Bijak, Daniel Courgeau and Robert Franck.  We submitted it to Population and Development Review — first we have to undergo a two-month-long preliminary review process, followed by a full review that could take several more months!  Hopefully the demography community finds it to be worth the wait 🙂

Abstract follows:

This paper aims to contribute to the debate on the future of demography. First we call attention to the developments of the discipline since the XVIIth century, and we describe its four successive paradigms related to the period, cohort, event-history and multilevel perspectives. We argue that these paradigms are complementary and that demography, since its beginnings, has subscribed to the classical scientific research programme launched by the promoters of modern science. Next we examine how simulation modelling may respond to three main challenges: how to overcome complexity in social research; how to reduce its uncertainty; and how to reinforce its theoretical foundations. We sketch a new paradigm for demography, system-based modelling, looking at interactions between various population systems. We then show how this new paradigm might conform to the classical scientific research programme, in order to take advantage of its benefits. We conclude with a tentative programme for the future of demography.

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Jan 16 2014
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Conferences, News, Philosophy, Publications

Paper forthcoming in Demographic Research (again!)

Yes, we have another paper coming soon, this one with a rather methodological/philosophical bent, called Quantifying Paradigm Change in Demography.  This was a collaborative piece of work with eminent French demographer Daniel Courgeau and philosopher of science Robert Franck (check out their 2007 book) focused on the development of a new research paradigm in the field of demography.

Demography is a field with a long history, dating back to the 17th century.  In those 350 years, we have seen the field progress through a series of paradigmatic shifts, from early efforts in period analysis through to more modern efforts in multilevel modelling and microsimulation.  Most recently, we have seen a great deal of interest in agent-based simulation techniques, which many hope will allow demography to uncover the ‘micro-macro link’ — the processes by which individual behaviours produce higher-level social complexity.

In this paper we analyse the demographic literature to delineate when these changes occurred and uncover how the field itself has evolved in response to new challenges.  This started as a side-project within an ongoing research effort, intended for Population and Development Review, and blossomed into a separate piece of research.

This paper was accepted shortly before Christmas, and just a few days ago we submitted the final version, which will be edited and published in late February/early March.

Next the four of us will be submitting both that paper for PDR and a short paper for the upcoming agent-based modelling workshop in Leuven in September.

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Nov 03 2013
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News, Publications

Paper published in JASSS!

Very excited to say that my paper with several close Care Life Cycle Project colleagues is now available in the Journal of Artificial Societies and Social Simulation, an excellent free and open-access journal focusing on the simulation of social systems.

Our paper is called When Demography Met Social Simulation: A Tale of Two Modelling Approaches and presents a proof-of-concept model linking agent-based simulation with statistical demographic modelling.  Please cite widely 🙂

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Oct 16 2013
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Conferences, Publications

New papers submitted to Chaire Quetelet 2013

I’m excited to be involved in the upcoming Chaire Quetelet 2013, a seminar focusing on changes in the field of demography over the last 50 years and how we see the field changing in the next 50.  Many well-known faces from the field will be present for the discussion — some speaking in English, others speaking in French! — and it will certainly be a stimulating and challenging forum.

I’ve had the pleasure of collaborating on two papers for the seminar with Daniel Courgeau, Robert Franck, and Jakub Bijak.  We’ve recently submitted the final papers and you can access them in PDF form here:

Quantifying paradigm change in demography

Are the four Baconian Idols still alive in demography?

Feel free to download, ponder and send your comments!  They’re available on my ResearchGate and Academia.edu pages as well.

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Oct 09 2013
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Demographic Research paper is out!

Our paper for the journal Demographic Research just came out today!  After months of hard work it’s so satisfying to see it out there, and we love Demographic Research — they’re open-access too, so feel free to download to your heart’s content and spread it widely.

Next up will be our paper for the Journal of Artificial Societies and Social Simulation; the final version has been submitted to the editor so it won’t be long now.  Always good to have these things done; now we’re able to move on to the next paper!

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Aug 24 2013
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Paper accepted to Demographic Research

Got the news recently that a paper by Jakub Bijak, Jason Hilton and myself has been accepted for publication in Demographic Research, an open-access journal for demography and population sciences.  We’re very pleased to see our work accepted, particularly as we’re offering up a relatively unconventional approach.

We’ve just sent in the final version for editing/formatting, so it won’t be online for a little while.  In the meantime here’s the abstract:

Reforging the Wedding Ring:  Exploring a Semi-Artificial Model of Population for the United Kingdom with Gaussian Process Emulators

Background We extend the ‘Wedding Ring’ agent-based model of marriage formation to include some empirical information on the natural population change for the United Kingdom together with behavioural explanations that drive the observed nuptiality trends.

Objective  We propose a method to  explore statistical properties of agent-based  demographic models.  By coupling rule-based explanations driving the agent-based model with observed data we wish to bring agent-based modelling and demographic analysis closer together.  

Methods We present a Semi-Artificial Model of Population, which aims to bridge demographic micro-simulation and agent-based traditions.  We then utilise a Gaussian process emulator  – a statistical model of the base model – to analyse the impact of selected model parameters on two key model outputs: population size and share of married  agents.  A sensitivity analysis is attempted, aiming to assess the relative importance of different inputs.

Results The resulting multi-state model of population dynamics has enhanced predictive capacity as compared to the original specification of the Wedding Ring, but there are some trade-offs between the outputs  considered.   The sensitivity analysis  allows  identification of  the most important parameters in the modelled marriage formation process.  

Conclusions  The proposed methods allow for generating coherent, multi-level agent-based scenarios aligned with  some aspects of empirical demographic reality.  Emulators permit a statistical analysis of their properties and help select plausible parameter values.

Comments Given non-linearities in agent-based models such as the Wedding Ring, and the presence of feedback loops, the uncertainty of the model may not be directly computable by using traditional statistical methods.  The use of statistical emulators offers a way forward.

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