J. Doyne Farmer’s research while affiliated with University of Oxford and other places

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Publications (299)


Figure 2: Forecasts for real GDP, consumption, and investment for Austria from 2015-Q1 to 2018-Q1.
summarizes these data sources.
Forecasting Macroeconomic Dynamics using a Calibrated Data-Driven Agent-based Model
  • Preprint
  • File available

September 2024

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74 Reads

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J. Doyne Farmer

In the last few years, economic agent-based models have made the transition from qualitative models calibrated to match stylised facts to quantitative models for time series forecasting, and in some cases, their predictions have performed as well or better than those of standard models (see, e.g. Poledna et al. (2023a); Hommes et al. (2022); Pichler et al. (2022)). Here, we build on the model of Poledna et al., adding several new features such as housing markets, realistic synthetic populations of individuals with income, wealth and consumption heterogeneity, enhanced behavioural rules and market mechanisms, and an enhanced credit market. We calibrate our model for all 38 OECD member countries using state-of-the-art approximate Bayesian inference methods and test it by making out-of-sample forecasts. It outperforms both the Poledna and AR(1) time series models by a highly statistically significant margin. Our model is built within a platform we have developed, making it easy to build, run, and evaluate alternative models, which we hope will encourage future work in this area.

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Measuring productivity dispersion: a parametric approach using the Lévy alpha-stable distribution

May 2024

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7 Reads

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1 Citation

Industrial and Corporate Change

It is well known that value added (VA) per worker is extremely heterogeneous among firms, but relatively little has been done to characterize this heterogeneity more precisely. Here, we show that the distribution of VA per worker exhibits heavy tails, a very large support, and consistently features a proportion of negative values, which prevents log transformation. We propose to model the distribution of VA per worker using the four-parameter Lévy stable distribution, a natural candidate deriving from the generalized central limit theorem, and we show that it is a better fit than key alternatives. Fitting a distribution allows us to capture dispersion through the tail exponent and scale parameters separately. We show that these parametric measures of dispersion can be useful to characterize the evolution of dispersion in recent years.


Datasets used in our main analysis for the United Kingdom (UK) and the United States (US).
Parameters of the instantaneous Ornstein-Uhlenbeck process. We use the procedure described in the text. m and k are in percent.
A comparison of the percentage of the time real interest rates that are negative for both the UK and the US and for both the data and the model simulation. The simulation values are averaged over 1000 simulations.
Discounting the Distant Future: What Do Historical Bond Prices Imply about the Long-Term Discount Rate?

February 2024

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58 Reads

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6 Citations

Mathematics

We present a thorough empirical study on real interest rates by also including risk aversion through the introduction of the market price of risk. From the viewpoint of complex systems science and its multidisciplinary approach, we use the theory of bond pricing to study the long-term discount rate to estimate the rate when taking historical US and UK data, and to further contribute to the discussion about the urgency of climate action in the context of environmental economics and stochastic methods. Century-long historical records of 3-month bonds, 10-year bonds, and inflation allow us to estimate real interest rates for the UK and the US. Real interest rates are negative about a third of the time and the real yield curves are inverted more than a third of the time, sometimes by substantial amounts. This rules out most of the standard bond-pricing models, which are designed for nominal rates that are assumed to be positive. We, therefore, use the Ornstein–Uhlenbeck model, which allows negative rates and gives a good match to inversions of the yield curve. We derive the discount function using the method of Fourier transforms and fit it to the historical data. The estimated long-term discount rate is 1.7% for the UK and 2.2% for the US. The value of 1.4% used by Stern is less than a standard deviation from our estimated long-run return rate for the UK, and less than two standard deviations of the estimated value for the US. All of this once more reinforces the need for immediate and substantial spending to combat climate change.






The unequal effects of the health–economy trade-off during the COVID-19 pandemic

November 2023

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94 Reads

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25 Citations

Nature Human Behaviour

Despite the global impact of the coronavirus disease 2019 pandemic, the question of whether mandated interventions have similar economic and public health effects as spontaneous behavioural change remains unresolved. Addressing this question, and understanding differential effects across socioeconomic groups, requires building quantitative and fine-grained mechanistic models. Here we introduce a data-driven, granular, agent-based model that simulates epidemic and economic outcomes across industries, occupations and income levels. We validate the model by reproducing key outcomes of the first wave of coronavirus disease 2019 in the New York metropolitan area. The key mechanism coupling the epidemic and economic modules is the reduction in consumption due to fear of infection. In counterfactual experiments, we show that a similar trade-off between epidemic and economic outcomes exists both when individuals change their behaviour due to fear of infection and when non-pharmaceutical interventions are imposed. Low-income workers, who perform in-person occupations in customer-facing industries, face the strongest trade-off.



Citations (43)


... The high past failure rates indicate a limited reliability of project announcements published by industry, which may announce green hydrogen projects for strategic reasons, such as raising attention or attracting subsidies. Although sobering, this can provide valuable insights for realistic scale-up analyses of green hydrogen 31 and other low-carbon energy technologies in feasibility studies [44][45][46] , some of which 45 have recently faced criticism for lacking statistical rigour 47 . Our results are particularly useful for analyses that use uncertain project announcements as input data 25,48 . ...

Reference:

The green hydrogen ambition and implementation gap
The need for better statistical testing in data-driven energy technology modeling
  • Citing Article
  • August 2024

Joule

... It is thus little wonder that the estimation of long-run discount rate has vast repercussions and it has been the object of intense work and controversy over conflicting estimates between relatively low rates, as the ones advocated by Stern [40], and the higher rates of Nordhaus [41,42]. The choice of a proper long-run discount rate has enormous repercussions on longrun environmental planning and in latter years a number of empirical results have appeared on this matter [43][44][45][46][47][48][49][50][51] and the issue is far from being settled. Most recent discussions, specially from those that call for immediate action, argue that climate, intergenerational and financial uncertainties are not properly handled and that more work is necessary when exploring in practical terms the effect of specific interventions to, for instance, carbon prices [52][53][54][55][56][57]. ...

Discounting the Distant Future: What Do Historical Bond Prices Imply about the Long-Term Discount Rate?

Mathematics

... Our work is related to an expanding body of literature that employs ABMs to capture the heterogeneity and complexity of local and national housing markets. This research stream has its origins in the seminal works of Geanakoplos et al. (2012) and Axtell et al. (2014), who developed an ABM to represent the housing market in Washington DC and explore the origins of its house price cycle. After expanding this original model with life-cycle dynamics, an autonomous rental market and a dynamic buy-to-let (BTL) sector, Baptista et al. (2016) and Carro et al. (2022) turn their attention to assessing the impact of borrower-based macroprudential instruments on the UK housing market. ...

An Agent-Based Model of the Housing Market Bubble in Metropolitan Washington D.C.
  • Citing Article
  • January 2024

SSRN Electronic Journal

... Alternatively, we could take a Bayesian approach and select parameter combinations with a probability that is inversely proportional to the loss. Common Bayesian methods include Approximate Bayesian Computation , Kernel Density Estimation (Grazzini et al., 2017) and Neural Posterior Estimation (Dyer et al., 2024). ...

Black-box Bayesian inference for agent-based models
  • Citing Article
  • February 2024

Journal of Economic Dynamics and Control

... The remaining studies applied different methods such as sensitivity analysis or Monte Carlo simulations to account for this issue. Apart from this, a broader availability of data could significantly increase the validity of the models, as the used parameters would be much more comparable, and modelers would not have to rely on individual data sources [86]. Modelers might also be able to address this uncertainty by using conservative predictions, apply sensitivity analyses, use the latest available data, and update their models accordingly to strengthen their results [87]. ...

Economic modelling fit for the demands of energy decision makers
  • Citing Article
  • February 2024

Nature Energy

... In differentiable simulations, the models are implemented to be differentiable, such that gradients obtained via automatic differentiation [18] can be used for efficient learning and control. Thus far, differentiable simulation has been intensively applied to physical problems [19,20,21], but the scope of its application has recently been extending to agent-based social simulations [22,23,24,25]. Recent studies have reported that the differentiability of the simulator enables system identification [26] or parameter estimation [23] based on the loss between simulation and observation. ...

Gradient-Assisted Calibration for Financial Agent-Based Models
  • Citing Conference Paper
  • November 2023

... Second, despite the wealth of epidemiological knowledge encoded in unstructured and multimodal data sources (e.g., satellite imagery, social media, electronic health records), their incorporation into mechanistic models has largely relied on manual feature extraction, hindering the effective utilization of the richness of these data [15][16][17] . Third, the rise of big data 18,19 has spurred the development of more complex mechanistic models that offer granular and detailed descriptions of disease dynamics 20,21 , but also increase the computational resources required for model calibration and validation, epidemic simulation, and optimization. ...

The unequal effects of the health–economy trade-off during the COVID-19 pandemic

Nature Human Behaviour

... At the same time, high urban connectivity allows shocks to cascade across time, space and system components. Examples of urban networks include labour markets 4 , global supply chains 5,6 , networks of social encounters 7 and infrastructure networks 8 . Understanding the spread of shocks across urban spaces, among businesses and urban amenities, is crucial for resilient urban planning policies, which aim to mitigate disruptions and to improve the recovery speed and quality of businesses and organizations in cities 9 . ...

Building an alliance to map global supply networks
  • Citing Article
  • October 2023

Science

... The assumptions here are legitimate: a larger increase in GMT will lead, on average, to more extreme heat and heatwaves, more intense rainfall and so on (IPCC et al 2021) and a smaller increase in GMT will reduce the risk of these impacts (IPCC 2018). Ranger et al (2022) discuss the NGFS methodology and the challenges with using IAMs (see also Farmer et al 2015, Stern 2016, Pindyck 2017, Hepburn and Farmer 2020 given these models do not reflect the importance of extremes and were not designed to explore uncertainties. ...

Less precision, more truth: uncertainty in climate economics and macroprudential policy
  • Citing Chapter
  • June 2020

... Attributes and initial conditions may also include the network connecting the agents. Here, most efforts in economics have focused on reconstructing production (Ialongo et al., 2022;Mungo et al., 2023) and financial (Anand et al., 2018) networks. There is also a large literature on regionalization of input-output models (Bonfiglio and Chelli, 2008). ...

Reconstructing production networks using machine learning
  • Citing Article
  • February 2023

Journal of Economic Dynamics and Control