Natural Experiments Research Articles

Call for papers: Generating stronger evidence to inform policy and practice: natural experiments on built environments, health behaviours and chronic diseases

Call for papers: Generating stronger evidence to inform policy and practice: natural experiments on built environments, health behaviours and chronic diseases

Using Natural Experiments in Public Enterprise Management

Using Natural Experiments in Public Enterprise Management

The effect of obtaining EU citizenship in former transition economies on remittance flows

AbstractWe estimate the effect of the granting of European Union (EU) citizenship rights on the flow of remittances from Italy. We use the EU enlargements of 2007 and 2013 as natural experiments. The results show a negative impact on remittance flows. The effect of the 2007 EU enlargement shows how Romanian and Bulgarian citizens reduced the average annual amount of remittances by 1400 Euros per year per migrant. In the case of the 2013 EU enlargement, we find a smaller decrease of about 50 Euros per year per Croat. These results are consistent after a series of robustness checks. We analyse this decline in depth to the extent that remittances are an important source of monetary flows in transition economies. We find that both the change in the taxonomy of immigrants from the new Member States and the improvement of economic conditions in the country of origin after the EU accession provide suggestive evidence on plausible mechanisms behind our results.

How much schizophrenia do famines cause?

Since the 1970s, famines have been widely invoked as natural experiments in research into the long-term impact of foetal exposure to nutritional shocks. That research has produced compelling evidence for a robust link between foetal exposure and the odds of developing schizophrenia. However, the implications of that research for the human cost of famines in the longer run have not been investigated. We address the connection between foetal origins and schizophrenia with that question in mind. The impact turns out to be very modest—much less than one per cent of the associated famine death tolls—across a selection of case studies.

USE OF AQUEOUS EMULSIONS OF WASTE MOTOR OILS AS HIGH-EFFICIENCY FUEL

This work presents the methodology of using wasted lubricants as a highly efficient fuel as water-fuel emulsions, which containing up to 70% water. They burning in burners under conditions of action high-frequency electrical discharges. It has been shown that the viscosity of a water-oil emulsion with a high water part (more than 50%) outweighs the viscosity of pure oil. With a low water part (10-20%), the emulsion is the most stable. With more water, the semi-delamination time decreases. Therefore, it is necessary to spray the emulsion near the site of the making. The results of natural experiments and prospects of the proposed methodology are given. Combustion of a water-in-oil emulsion with a volume content of 50-70% water is possible in the presence of a discharge of high-frequency signals. Independent combustion of the emulsion without the support of a small diesel fuel torch is possible with sufficient heating of the combustion chamber. To implement combustion, the burner for liquid fuels was modernized by adding a pre-chamber between the burner and the nozzle or boiler. To organize effective spraying of water-oil emulsion with a large amount of water (up to 70%), it is necessary to ensure sufficient heating of the emulsion in the pipelines. First, this reduces its viscosity, making it easier to pump the emulsion through the supply systems of the spraying device. Otherwise, it is necessary to serve under a pressure, so that the water at a high temperature (above 100 ° C) is remained liquid. When leaving the nozzle under pressure, the water “boils” (“micro-bump” drops of emulsion), which further disperses the burning liquid. The peculiarity of this burner is the action of a high-frequency streamer in the area of spraying emulsion droplets inside the forechamber. The use of water-fuel emulsions allows to reduce emissions of nitrogen oxides and carbon monoxide, reduce its fire and explosion hazard during transportation and storage. Effectiveness assessment of this complex showed that energy expenditures can reach percents of levels compared to full heat release.Thus, the possibility of using such water-oil emulsions as alternative fuels is shown. Keywords: water-oil emulsion, high-frequency electric discharge, combustion, torch.

Natural Experiments as a Study Method in Spinal Trauma Surgery: A Systematic Review.

Systematic review. To determine if the natural experiment design is a useful research methodology concept in spinal trauma care, and to determine if this methodology can be a viable alternative when randomized controlled trials are either infeasible or unethical. A Medline, Embase and Cochrane database search was performed between 2004 and 2023 for studies comparing different treatment modalities of spinal trauma. All observational studies with a natural experiment design comparing different treatment modalities of spinal trauma were included. Data extraction and quality assessment with the MINORS criteria was performed. Four studies with a natural experiment design regarding patients with traumatic spinal fractures were included. All studies were retrospective, one study collected follow-up data prospectively. Three studies compared different operative treatment modalities, whereas one study compared different antibiotic treatment strategies. Two studies compared preferred treatment modalities between expertise centers, one study between departments (neuro- and orthopedic surgery) and one amongst surgeons. For the included retrospective studies, MINORS scores (maximum score 18) were high ranging from 12-17 and with a mean (SD) of 14.6 (1.63). Since 2004 only four studies using a natural experiment design have been conducted in spinal trauma. In the included studies, comparability of patient groups was high emphasizing the potential of natural experiments in spinal trauma research. Natural experiments design should be considered more frequently in future research in spinal trauma as they may help to address difficult clinical problems when RCT's are infeasible or unethical.

An Evidence-based Meta-analysis on the Outcomes of Teacher Education under the Concept of Outcome-Based Education

Currently, there is limited empirical research on the educational outcomes of Outcome-based Education (OBE) theory, making it challenging to draw clear inferences based on logical deductions in real-world contexts. Taking a certain university in Wuhan city as an example, this study conducted 50 regression analyses on the curriculum as the research subject, employing both Meta-analysis and Meta-regression analysis as natural experiments. The findings reveal that the implementation of OBE reforms significantly enhances the educational outcomes of teachers, although the impact shows substantial heterogeneity. Firstly, the classroom learning environment has a significant positive impact on educational outcomes. Secondly, the study found that implementing OBE reforms has significantly positive effects on professional courses and platform courses, while showing insignificant effects on general education and elective courses. Thirdly, the effects of OBE reforms are more pronounced for students in science and engineering as well as business and management disciplines, whereas insignificant for students in humanities and arts disciplines. Based on these findings, the following policy recommendations are proposed: there should be a firm commitment to the implementation of OBE reforms, and it is advisable to expand the scope of OBE reforms to a larger scale. Furthermore, OBE reforms can be selectively implemented across all courses, and efforts should be made to ensure clarity of objectives when implementing OBE reforms in disciplines related to humanities and arts.

Prioritizing a research agenda on built environments and physical activity: a twin panel Delphi consensus process with researchers and knowledge users

BackgroundThe growth of urban dwelling populations globally has led to rapid increases of research and policy initiatives addressing associations between the built environment and physical activity (PA). Given this rapid proliferation, it is important to identify priority areas and research questions for moving the field forward. The objective of this study was to identify and compare research priorities on the built environment and PA among researchers and knowledge users (e.g., policy makers, practitioners).MethodsBetween September 2022 and April 2023, a three-round, modified Delphi survey was conducted among two independent panels of international researchers (n = 38) and knowledge users (n = 23) to identify similarities and differences in perceived research priorities on the built environment and PA and generate twin ‘top 10’ lists of the most important research needs.ResultsFrom a broad range of self-identified issues, both panels ranked in common the most pressing research priorities including stronger study designs such as natural experiments, research that examines inequalities and inequities, establishing the cost effectiveness of interventions, safety and injuries related to engagement in active transportation (AT), and considerations for climate change and climate adaptation. Additional priorities identified by researchers included: implementation science, research that incorporates Indigenous perspectives, land-use policies, built environments that support active aging, and participatory research. Additional priorities identified by knowledge users included: built environments and PA among people living with disabilities and a need for national data on trip chaining, multi-modal travel, and non-work or school-related AT.ConclusionsFive common research priorities between the two groups emerged, including (1) to better understand causality, (2) interactions with the natural environment, (3) economic evaluations, (4) social disparities, and (5) preventable AT-related injuries. The findings may help set directions for future research, interdisciplinary and intersectoral collaborations, and funding opportunities.

Virulence of Dothistroma septosporum and D. pini on Pinus nigra and P. mugo under conditions of natural infection

AbstractDothistroma needle blight (DNB) is a severe needle disease of pines worldwide, caused by two closely related species, Dothistroma septosporum and D. pini. The two fungal species are similar not only in their morphological characteristics, but also cause very similar symptoms in their hosts, and have a similar ecology. The aim of this study was to compare the virulence of the two Dothistroma species in natural infection experiments on 2-year-old seedlings of two DNB susceptible pine species, Pinus nigra and P. mugo, in two seedling stands for each pathogen species. The virulence of the pathogens and presence of symptoms (symptomatic needles, red bands and acervuli) were assessed after 2 years of exposure to inoculum. The incidence of seedlings with DNB symptoms was 65% and 76% for P. nigra and P. mugo, respectively. No difference was found between D. septosporum and D. pini in any of the three DNB symptoms evaluated on seedlings of P. mugo. However, symptoms of disease differed between the two Dothistroma species on P. nigra. Variables that reflect the intensity of disease development, the number of red bands and acervuli per needle, showed a difference in virulence between D. septosporum and D. pini, but only in the case of the host species P. nigra. The results suggest that the virulence of the two Dothistroma species could be affected by host pine species and that there are differences in the susceptibility of individual pine species to D. septosporum and D. pini. Further factors could affect the virulence of these pathogens, including isolate origin, climatic or environmental factors.

Call for papers: Generating stronger evidence to inform policy and practice: natural experiments on built environments, health behaviours and chronic diseases

Call for papers: Generating stronger evidence to inform policy and practice: natural experiments on built environments, health behaviours and chronic diseases

Causal attribution of agricultural expansion in a small island system using approximate Bayesian computation

The extent and arrangement of land cover types on our planet directly affects biodiversity, carbon storage, water quality, and many other critical social and ecological conditions at virtually all scales. Given the fundamental importance of land cover, a key mandate for land system scientists is to describe the mechanisms by which pertinent cover types spread and shrink. Identifying causal drivers of change is challenging however, because land systems, such as small-scale agricultural communities, do not lend themselves well to controlled experimentation for logistical and ethical reasons. Even natural experiments in these systems can produce only limited causal inference as they often contain unobserved confounding drivers of land cover change and complex feedbacks between drivers and outcomes. Land system scientists commonly grapple with this complexity by using computer simulations to explicitly delineate hypothesized causal pathways that could have resulted in observed land cover change. Yet, land system science lacks a systematic method for comparing multiple hypothesized pathways and quantifying the probability that a given simulated causal process was in fact responsible for the patterns observed. Here we use a case study of agricultural expansion in Pemba, Tanzania to demonstrate how approximate Bayesian computation (ABC) provides a straightforward solution to this methodological gap. Specifically, we pair an individual-based simulation of land cover change in Pemba with ABC to probabilistically estimate the likelihood that observed deforestation from 2018 to 2021 was driven by soil degradation rather than external market forces. Using this approach, we can show not only how well a specific hypothesized mechanism fits with empirical data on land cover change, but we can also quantify the range of other mechanisms that could have reasonably produced the same outcome (i.e. equifinality). While ABC was developed for use in population genetics, we argue that it is particularly promising as a tool for causal inference for land system science given the wealth of data available in the satellite record. Thus, this paper demonstrates a robust process for identifying the emergent landscape-level signatures of complex social-ecological mechanisms.

Study and Application of Estimation Method for Environmental Background Pollution Fluxes into the River in Source Areas

The background values of pollutants are becoming increasingly prominent in evaluating water quality and management, and their load and output characteristics are of great significance to the study of changes in the background values. Thus, this paper studies the estimation method for background pollutant fluxes into a river in a forested river source in northeastern China with deficient data or without data. Based on the results of a soak experiment and leaching experiment, as well as natural rainfall runoff experiments, the conversion relationship of the pollutant concentration in the medium was established, the transformation relationship of the pollutant concentration in the medium was established, its load into the river in a small watershed was estimated, and the estimation method was verified according to the measurements (average relative error: 20.5%). Then, the background pollutant loading into the river was calculated on a large scale by improving the pollutant output coefficient model and the universal soil loss equation (average relative error: 18.7%, 24.7%). The results show that the method mentioned above can better reflect the background pollutant loading into the river. This study provides an effective strategy to estimate the background pollutant loading into rivers in areas without data or with missing data, and also provides a theoretical basis for the study of zoning and the formulation of a water environment evaluation system based on background values.

On the stability of preferences: Experimental evidence from two disasters

We investigate the impacts of two disasters in Japan and the Philippines on preferences using the convex time budget experiments and multiple price list experiments with monetary rewards. By exploiting natural experiments which are combined with lab-in-the-field experiments, we aim to investigate whether and how long preferences are affected by extreme events. We find evidence supporting preference instability caused by exposure to natural hazards: in both our study sites, disaster exposure seems to make individuals more present-biased even though they differ in socioeconomic conditions and disaster types. The estimated impacts are persistent over the short and long time intervals in both disaster-affected areas and are robust to the method of measuring preferences.

Call for papers: Generating stronger evidence to inform policy and practice: natural experiments on built environments, health behaviours and chronic diseases

Call for papers: Generating stronger evidence to inform policy and practice: natural experiments on built environments, health behaviours and chronic diseases

Using Natural Experiments to Uncover Effects of Anti-Refugee Riots on Attitudes of Refugees

While previous research has focused on terrorist attacks and natives’ attitudes towards immigration, we examine the effect of anti-refugee attacks on refugees’ attitude towards the host country. We use survey data from the 33rd wave of the German Socio-Economic Panel as the fieldwork period overlapped with the infamous anti-refugee riots in Bautzen and as the survey includes a refugee sample. Making use of this natural experiment, we find significant and negative short-term effects of the riots on respondents’ perception of Germany, as well as low geographic variation. Such natural experiments in the form of unexpected events during survey design offer social scientists the possibilities to identify causal effects from observational survey data as they split respondents into a control and treatment group. Given the vast amount of (cross-)national survey data, often including specific subsamples, our study demonstrates the great potential of natural experiments for sociological research on minority groups in society.

OM Forum—In-Person or Virtual? What Will Operations Management/Research Conferences Look Like?

Problem definition: We examine the environmental implications of shifting from in-person to virtual conference formats and identify the effects of such a shift on the value conferences provide to our societies. We extend work from other fields to present a more comprehensive comparison of the environmental impact and perceived value of different conference formats for the operations management/research communities. Methodology/results: We leverage a series of COVID-19–induced natural experiments to precisely evaluate the environmental footprint and societal value difference between in-person and virtual formats via life cycle assessment and survey techniques, respectively. Specifically, we focus on Institute for Operations Research and the Management Sciences, Production and Operations Management Society, and European Operations Management Association conferences that were conducted in both formats between 2019 and 2021. The environmental assessment reveals a huge impact reduction: for climate change, on average, from 941.9 kg CO2eq per person for in-person formats to 1.0 for virtual. The value assessment emphasizes, instead, a detrimental utility loss with the overall perceived value derived from attendance moving—on a scale from 0 to 10—on average, from 7.9 to 4.0. When investigating the drivers of conference valuation, virtual formats show some merits, such as lower perceived costs and the added value of flexibility. The preference for in-person formats is unambiguous though, justified by the large performance gap related to socialization and networking, the two most important value drivers identified by our analysis. Managerial implications: These results highlight an inherent trade-off between virtual and in-person conferences. To overcome it, we discuss four strategies as to how our societies can reduce their environmental footprints and remain true to their essential purpose: (1) reduce in-person impact, (2) improve virtual design, (3) hybrid and decentralized formats, and (4) revise conferencing model and societies’ role. Supplemental Material: The online appendix is available at https://doi.org/10.1287/msom.2022.0591 .

3.C. Skills building seminar: Guidance on using natural experiments to evaluate population health interventions

Abstract There has been a substantial increase in the conduct of natural experimental evaluations since original guidance was published. There have been advances in relevant methodologies, greater availability of big datasets, and a rise in demand for ‘what works’ evidence amenable to natural experimental evaluation. Therefore, it is important that researchers, public health practitioners, funders, and users of intervention research are aware of recent developments and of the strengths, weaknesses, and applicability of natural experimental evaluations. Updated and extended guidance has been developed for using natural experiments to evaluate population health interventions. Guidance was developed from three international workshops and an online consultation with researchers, journal editors and end users of natural experimental evaluations. The project was funded by The UK Medical Research Council and the National Institute for Health and Care Research, and the project team comprised researchers with expertise in natural experimental evaluations. The project had a funder-assigned oversight group and an advisory group of independent experts, including researchers and practitioners with experience of commissioning natural experimental evaluations. This updated and extended guidance provides an integrated guide to the use of natural experimental methods to evaluate population health interventions, offering a range of tools to support its use and detailed, evidence-based information for researchers, funders, publishers, and users of evidence. The objective of this skills building seminar is to upskill public health researchers and practitioners on the design and use of natural experimental methods. The seminar will present key aspects of the guidance and provide the opportunity to discuss and explore each aspect. The first presentation will highlight important considerations when designing and planning a natural experimental evaluation and introduce recommendations for planning, commissioning, conducting, and using evidence from natural experimental evaluations. The second presentation will outline the value and roles of qualitative methods, explaining how qualitative evidence strengthens evaluations. There will then be a discussion and collaborative learning session, providing an opportunity for researchers and public health practitioners to share experiences and engage with the guidance. The discussions will be prompted by examples of natural experimental evaluations relevant to the presentations. Key messages • Natural experimental evaluations are valuable for assessing the impacts of population health interventions. • This workshop provides an opportunity to engage with and discuss new guidance, highlighting good practice in the design, planning, conduct and use of evidence from natural experimental evaluations.

Designing and planning natural experimental evaluations with good practice recommendations

Abstract Background There have been significant developments in methods, infrastructure, and data availability for natural experimental evaluations. The rise in the use of natural experimental approaches means it is important that researchers, public health practitioners, funders, and users of intervention research understand the phases involved when designing and planning a natural experimental evaluation and are aware of good practice considerations. Methods Guidance was developed from three international workshops and an online consultation with researchers, journal editors and end users of natural experimental evaluations. The project team comprised researchers with expertise in natural experimental evaluations. The project included an oversight group and an advisory group of independent experts. Results The design and planning of an evaluation involves understanding the definition of a natural experiment, being aware of opportunities for a natural experimental evaluation and the relevance of a systems perspective and mixed methods approaches. The practicalities of planning an evaluation involve assessing the evaluability and feasibility of the evaluation and identifying and involving stakeholders throughout the process. Good practice considerations include understanding the evaluation design and planning processes, engaging stakeholders, and recognising the respective strengths of different analytical approaches. Recommendations for policymakers, public health practitioners and commissioners of evaluations include recognising and using high quality evaluations and incorporating evaluation plans into the implementation of new policies and programmes. Conclusions Understanding the processes involved in designing and planning a natural experimental evaluation are important to successfully conducting and evaluating natural experiment interventions.

Value and roles of qualitative methods in natural experimental evaluations

Abstract Background For natural experimental evaluations that estimate effect sizes of population health interventions, qualitative evidence contributes multiple benefits. Incorporating qualitative methods strengthens natural experimental evaluations, particularly when studying interventions in complex systems, and contributes to minimising evaluation design weaknesses. Methods Guidance was developed from three international workshops and an online consultation with researchers, journal editors and end users of natural experimental evaluations. The project team comprised researchers with expertise in natural experimental evaluations. The project included an oversight group and an advisory group of independent experts, including researchers, a journal editor, and scientific and public health advisors on central and local government. Results The guidance recommends that most evaluations of natural experiments will require the inclusion of qualitative evidence. Qualitative methods are valuable when describing the natural experiment intervention, the system and context it exists within, and theories of change. Qualitative work can help appropriately define exposed and unexposed groups, investigate causal mechanisms, facilitate meaningful selection of outcomes, and understand stakeholder perspectives on the intervention and its effects. Conclusions Gaining an understanding of the value and application of qualitative evidence will help producers and users of natural experimental evaluations conduct and identify robust evaluations. To fully benefit the evaluation, qualitative methods should be integrated throughout.

Four recommendations to tackle the complex reality of transdisciplinary, natural experiment research.

Natural experiments are often used to study interventions in which randomization to control versus intervention conditions are impossible. Nature-based interventions (i.e., programs designed to increase human interaction with nature and improve human health) are commonly studied as natural experiments. We used a natural experiment design to explore the benefits of ecological rehabilitation of parks on biodiversity and resident health in low-income, minoritized neighborhoods in Detroit, MI. Given the complexities and interconnectedness of lived experiences, community needs, and ecological health, this research design has presented challenges. Based on our experiences, we pose four key recommendations for researchers and practitioners conducting natural experiments, nature-based interventions, and those working in low-income, minoritized neighborhoods. We use the explicit examples of challenges faced as rationale for these recommendations. The key recommendations are (1) Engage with community leaders; (2) Build a transdisciplinary team and work closely; (3) Examine privilege; and (4) Create a unified vision.