Synthetic Control Research Articles

Federating governance, access and infrastructure to support researcher use of synthetic data

Synthetic Data has the potential to improve efficiency of data analysis for researchers. However, there is no standard approach to synthetic data governance, access controls or infrastructure requirements, and researchers may face inconsistencies in how they can access or use synthetic data across trusted research environments. We present a federated solution taken by the Scottish Safe Haven Network to address these barriers to facilitate researcher use of synthetic data. We documented and evaluated existing governance pathways, access controls and infrastructure design for non-synthetic data across the Network, recognising uniformity and establishing equivalence using the 5 Safes framework, ISO27001 standards and the SATRE TRE specification. We also interviewed current and potential researchers using our trusted research environments to identify common use cases for accessing synthetic data. We then mapped researcher requirements against the documented equivalencies, validating with current and prospective users. We identified several use cases: to undertake feasibility studies, to understand dataset structure and format and to write analysis code whilst waiting on the project-specific data to be provided. By mapping the use cases onto existing governance and access processes and infrastructure designs, we were able to agree to a standard application process, access control mechanism, and infrastructure platform across the Network to provide a consistent process for researchers. A federated approach to synthetic data access will improve the speed at which research can be conducted as well as improving the transparency and consistency of data governance and access across organisations, ultimately improving the experience for researchers using TREs.

Prevalence of Congenital Anomalies Before and After Implementation of a Novel Wastewater Treatment Technology in Texas: An Augmented Synthetic Control Method Analysis Utilizing Data from a Population-Based Birth Defects Registry

Objective and ApproachDirect potable reuse (DPR) involves adding purified wastewater that has not passed through an environmental buffer into a water distribution system. This technology may address growing demand for water in many population centers, but there are no studies of health outcomes in populations receiving DPR-treated drinking water. Our objective was to determine whether the prevalence of congenital anomalies increased in the period following introduction of DPR-treated water to certain public water systems in Texas. We obtained data on all cases with congenital anomalies regardless of pregnancy outcome during 2003-2017 from the population-based Texas Birth Defects Registry. Maternal demographic and residential data were obtained and a reference population of all livebirths in Texas was identified by linkage to birth and fetal death records. The augmented synthetic control method was used to model county-level changes in prevalence of congenital anomalies (expressed per 10,000 livebirths) after the adoption of DPR by four Texas counties in mid-2013. County-level data on maternal age, education, ethnicity, and rural-urban status were included as covariates. Results: We observed increased prevalence of all congenital anomalies collectively (average treatment effect in the treated [ATT] = 53.6) and congenital heart disease (ATT = 287.3) during the years 2014-2017. Neural tube defects prevalence was unchanged. ConclusionsWe found evidence that the prevalence of congenital anomalies overall and congenital heart disease specifically increased during the years 2014-2017. ImplicationsAdditional research into reproductive and developmental outcomes among people in areas supplied with DPR-treated water is warranted to inform water policy decisions.

CaLi2PN3 - A Quaternary Chain-Type Nitridophosphate by Medium-Pressure Synthesis.

Nitridophosphates are in the focus of current research interest due to their structural versatility and properties, such as ion conductivity, ultra-incompressibility and luminescent properties when doped with suitable activator ions. Multinary representatives often require thorough investigation due to the competition with the thermodynamically more stable binary and ternary compounds. Another point of concern is the synthetic control of structural details, which is usually limited by conventional bottom-up syntheses. In this study, we report on the synthesis and characterization of the quaternary nitridophosphate CaLi2PN3. Various synthesis protocols were used for the preparation of CaLi2PN3, including the novel nitridophosphate double salt approach. The crystal structure was solved and refined from single-crystal X-ray diffraction data and confirmed by Rietveld refinement, solid-state NMR spectroscopy, EDX measurements and low-cost crystallographic calculations. The experimental results were corroborated by DFT calculations, which revealed the electronic band structure. Formation energy calculations allowed conclusions to be drawn about the stability in comparison to the initial ternary nitridophosphates. The synthesis of CaLi2PN3 exemplifies the enormous potential of medium-pressure syntheses in the field of nitridophosphate research. Furthermore, the presented new synthesis route allows a certain degree of structural control, which is a promising addition to previous synthesis strategies in nitridophosphate chemistry.

Seriation of Enzyme-Functionalized Multilayers for the Design of Scalable Biomimetic Mineralized Structures.

Biomimetic hydroxyapatites are widely explored for their potential applications in the repair of mineralized tissues, particularly dental enamel, which is acellular and, thus, not naturally reformed after damage. Enamel is formed with a highly-controlled hierarchical structure, which is difficult to replicate up to the macroscale. A biomimetic approach is thus warranted, based on the same principles that drive biomineralization in vivo. Herein, a strategy for the design of enamel-like architectures is described, utilizing enzymes embedded in polyelectrolyte multilayers to generate inorganic phosphate locally, and provide a favorable chemical environment for the nucleation and growth of minerals. Moreover, a method is proposed to build up seriated mineral layers with scalable thicknesses, continuous mineral growth, and tunable morphology. Results show the outstanding growth of cohesive mineral layers, yielding macroscopic standalone fluoride and/or carbonate-substituted hydroxyapatite materials with comparable crystal structure and composition to native human mineralized tissues. This strategy presents a promising path forward for the biomimetic design of biomineral materials, particularly relevant for restorative applications, with an exquisite level of synthetic control over multiple orders of magnitude.

No evidence of increased forest loss from a mining rush in Madagascar’s eastern rainforests

Artisanal and small-scale mining is an important livelihood activity in many biodiversity hotspots. There is substantial international concern about the negative impact of artisanal and small-scale mining on biodiversity, yet in most places this remains poorly understood. We explore the impacts of a high-profile mining rush: the 2016 sapphire rush at Bemainty, Eastern Madagascar, where tens of thousands of miners descended on a protected forest. Media coverage claimed the rush caused hundreds of hectares of deforestation and threatened lemur populations. Using the synthetic control method to estimate counterfactual outcomes, we find no evidence that mining increased forest loss or degradation. Supported by informal interviews and a lemur survey, we argue that mining at Bemainty had limited impacts on the surrounding forest, relative to other threats. Our results highlight the heterogeneity of environmental impacts from artisanal and small-scale mining and emphasize the need for more robust evaluations to inform context-specific policies.

Evaluating mangrove community forestry outcomes: a mixed synthetic control and field-based approach

Abstract Contemporary evaluations of outcomes in human-managed systems have been constrained by a lack of counterfactual analysis. Community forestry (CF), a widely adopted strategy to achieve both conservation and management in coupled human-environment systems, is no exception, and counterfactual analysis would greatly enhance CF research. We used a mixed method approach incorporating quantification of deforestation and forest regrowth rates, synthetic control analysis, and focus groups discussions to evaluate mangrove CF outcomes in the Ayeyarwady Delta, Myanmar, from to 1990–2021. CF resulted in an overall increase in net forest gain and reduction in net forest loss across sites. More than two-thirds of CF sites had superior outcomes relative to synthetic controls for at least one metric (deforestation or forest regrowth); however, CF tended to perform better for only one outcome while avoiding underperformance in the other. The annual rate of forest regrowth in CFs accelerated beginning three years prior to certification and peaked two years after certification, likely related to pre-certification engagement with the Forest Department or non-government organizations. Moreover, control sites near CFs experienced more rapid forest regrowth than controls further from CFs, suggesting spillover effects. The predominant challenge facing successful CF management was illegal extraction and overharvesting, and poor performing CFs experienced a complex array of challenges facing forest regrowth, likely related to the private nature of individual land claims within the CFs. Most supporting factors for CF were related to community management capacity, strongly indicating a need for extended close engagement with competent government and non-government actors to develop long-term management and governance capacities, which are sustainably funded. Our mixed-method approach can be replicated in other human-managed systems to evaluate the biophysical impacts of policies and gain insights into the underlying drivers of outcomes.

Surgical Risk, Operative Time, and Anesthesia Time Associated With Combining Tracheostomy and Gastrostomy Tube Placement Under a Single Anesthetic

IntroductionPediatric patients may need both tracheostomy and gastrostomy tube (G-tube) placement to satisfy both oxygen and nutritional requirements for sustaining life. It is unclear if combining both procedures under one anesthetic is associated with reductions in total operative time or surgical risk, compared to performing the two procedures separately. MethodsOur study used the 2016–2021 National Surgical Quality Improvement Program-Pediatric Participant Use Files. Patients age 0–2 years were included if they underwent elective tracheostomy or G-tube placement and no concomitant procedures other than direct laryngoscopy or bronchoscopy. The initial cohort included 14,047 patients undergoing G-tube placement only, 571 undergoing tracheostomy only, and 236 undergoing both procedures concurrently. Multivariable analysis used propensity score matching to compare combined procedures to matched synthetic controls, created by combining data from patients undergoing each procedure independently (N = 180 matched pairs). ResultsAfter matching, combined procedures were associated with lower complication risk (odds ratio: 0.42; 95% confidence interval [CI]: 0.27, 0.65) and reduced anesthesia time (mean difference: 57 min; 95% CI: 47, 68) when compared to synthetic controls, but did not differ on total operative time (mean difference: −4.5 min; 95% CI: −12.6, +3.6). ConclusionCombined procedures are theorized to reduce risks associated with prolonged exposure to anesthesia. We found a reduction in total anesthesia time associated with combining tracheostomy and G-tube placement under one anesthetic, and lower risk of complications, but no change in total operative time relative to performing 2 separate surgeries. Level of EvidenceIII.

An 'alcohol health champions' intervention to reduce alcohol harm in local communities: a mixed-methods evaluation of a natural experiment.

Globally alcohol consumption is a leading risk factor for premature death and disability and is associated with crime, social and economic consequences. Local communities may be able to play a role in addressing alcohol-related issues in their area. To evaluate the effectiveness and cost-benefit of an asset-based community development approach to reducing alcohol-related harm and understand the context and factors that enable or hinder its implementation. A mixed-methods evaluation. Area-level quasi-experimental trial analysed using four different evaluation methods (a stepped-wedge design where each area was a control until it entered the intervention, comparison to matched local/national controls and comparison to synthetic controls), alongside process and economic evaluations. Ten local authorities in Greater Manchester, England. The outcomes evaluation was analysed at an area level. Ninety-three lay persons representing nineareas completed questionnaires, with 12 follow-up interviews in five areas; 20 stakeholders representing ten areas were interviewed at baseline, with 17 follow-up interviews in eight areas and 26 members of the public from two areas attended focus groups. Professionals in a co-ordinator role recruited and supported lay volunteers who were trained to become alcohol health champions. The champion's role was to provide informal, brief alcohol advice to the local population and take action to strengthen restrictions on alcohol availability. Numbers of alcohol-related hospital admissions, accident and emergency attendances, ambulance call-outs, street-level crime and antisocial behaviour in the intervention areas (area size: 1600-5500 residents). Set-up and running costs were collected alongside process evaluation data exploring barriers and facilitators. Routinely collected quantitative data on outcome measures aggregated at the intervention area and matched control and synthetic control areas. Data from policy documents, licensing registers, meeting notes, invoices, time/cost diaries, training registers, questionnaires, interviews, reflective diaries and focus groups. The intervention rolled out in nine out of ten areas, seven of which ran for a full 12 months. Areas with better-established infrastructure at baseline were able to train more champions. In total, 123 alcohol health champions were trained (95 lay volunteers and 28 professionals): lay volunteers self-reported positive impact. Champions engaged in brief advice conversations more readily than taking action on alcohol availability. There were no consistent differences in the health and crime area-level indicators between intervention areas and controls, as confirmed by using three different analysis methods for evaluating natural experiments. The intervention was not found to be cost-beneficial. Although the sequential roll-out order of the intervention was randomised, the selection of the intervention areas was not. Self-reported impact may have been subject to social desirability bias due to the project's high profile. There was no measurable impact on health and crime outcomes. Possible explanations include too few volunteers trained, volunteers being unwilling to get involved in licensing decisions, or that the intervention has no direct impact on the selected outcomes. Future similar interventions should use a coproduced community outcomes framework. Other natural experiment evaluations should use methodological triangulation to strengthen inferences about effectiveness. This trial is registered as ISRCTN81942890. This award was funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme (NIHR award ref: 15/129/03) and is published in full in Public Health Research; Vol. 12, No. 9. See the NIHR Funding and Awards website for further award information.

Estimating the impact of wildlife damage compensation policy on farmers’ incomes

At present, the conflict between humans and wildlife in China is becoming more serious, and the wildlife damage compensation policy, as an important part of the ecological compensation system, has become an important means to alleviate the contradiction between wildlife protection and farm household development. This study empirically examines the mechanism of action and analyses the impact of the pilot wildlife damage compensation policy on farmers’ incomes, using Chinese provincial panel data from 2004 to 2021, and employing synthetic control methods, double difference models and moderated effects models. The results show that: (1) At the provincial level, the wildlife damage compensation policy can significantly increase farmers’ income by 16.7 %, which has been validated through a series of robustness tests. (2) Further analysis using micro-survey data shows that the wildlife compensation policy significantly increases farmers’ income by 22.5 %. (3) Mechanism analysis reveals that the wildlife damage compensation policy can increase rural agricultural employment by 4.3 %, thereby increasing farmers’ income. (4) Heterogeneity analyses indicate that wildlife damage compensation policy has different effects on farmers’ income. Among these, the impact on low-income farmers is more pronounced. Understanding the impact and heterogeneity of wildlife damage compensation policy on farmers’ income can facilitate the design of targeted compensation policies to address the mismatch between conservation and development, thereby achieving the policy objective of promoting a symbiotic coexistence between wildlife conservation and farmers’ economic interests.

Polynorepinephrine and polydopamine-bacterial laccase coatings for phenolic amperometric biosensors

The successful fabrication of biosensors is greatly limited by the immobilization of their bioreceptor, thus we propose a facile and reproducible two-step method to modify graphite electrodes with a bacterial laccase, relying on a fast and controllable potentiostatic process to coat graphite surfaces with biomolecule-compatible thin films of polynorepinephrine (ePNE) and polydopamine (ePDA). Both polymers, synthesized with a similar thickness, were functionalized with bacterial laccase, displaying distinct electrochemical transducing behaviours at pH 5.0 and 7.0. ePNE layer enables adequate electron transfer of anionic and cationic species in acidic and neutral media, whereas transduction across ePDA strongly depends on pH and redox probe charge. ePNE stands out by improving the amperometric responses of the biosensing interface towards a phenolic acid (gallic acid) and a flavonoid (catechin), in respect to ePDA. The optimal graphite/ePNE/laccase interface outperforms biosensing interfaces based on fungal laccases at neutral pH, displaying detection sensitivities of 104 and 14.4 µA cm−2 mM−1for gallic acid and catechin, respectively. The fine synthetic control of the ePNE bio-inspired transduction layer and the use of an alkaliphilic bacterial laccase enabled the construction of an amperometric biosensing interface with extended pH range of polyphenols detection present in food products and agro-industrial waste.

Multiple Narrowband Bidirectional Self‐Powered Organic Photodetector with Fast Response

AbstractBenefiting from the discovery of novel organic semiconductor materials bearing tunable absorption characteristics, narrowband organic photodetectors (OPDs) with improved performance are reported. Alongside new photoactive materials synthesis, several device engineering strategies are introduced to achieve narrowband OPDs, allowing less dependence of the device performance on the synthetic variation control, such as batch‐to‐batch differences in molecular weight. However, fabrication of multiband OPDs remains a challenge. Current solutions are usually based on vertical multi‐stacking of photosensitive layers with different absorption spectra and voltage‐modulated charge collection/injection, which renders the device fabrication too complex, while their response speed and band selectivity is limited. In this work, the concept of optical cavity is adopted to demonstrate self‐powered and fast response speed single‐junction bidirectional organic photodetectors with dual narrowband detection in the ultraviolet (UV) and visible part of the spectrum. Application of these devices in encrypted UV communication is successfully demonstrated. A third band in the near infrared (NIR) is possible to be isolated, rendering these high‐performing and simple to manufacture multiband OPD devices attractive for high‐resolution imaging and optical wireless communication.

The Brazilian Economy in the Recent Decades: an Analysis Using Synthetic Control

The Brazilian Economy in the Recent Decades: an Analysis Using Synthetic Control

Unveiling the Influence of Linkers on Conformations of Oligomeric Acceptors for High-Performance Polymer Solar Cells.

Conformational isomerism of organic photovoltaic materials has a profound impact on their molecular packing and therefore performance of polymer solar cells (PSCs). However, the conformations of oligomeric acceptors (OAs) are mostly predicted by simulations rather than experimental determinations. Herein, the stereochemical S-shaped structure of two dimeric-type acceptor molecules, V-DYIC and V-DYIC-4F, is first confirmed with different end groups (IC for V-DYIC and IC-2F for V-DYIC-4F), incorporating vinylene linkage for connecting the distinct state-of-the-art small molecule acceptor Y-segments. Through the synthetic control of fluorination sites adjacent to the vinyl-linker, S-shaped the conformation by NMR experiments is validated. Compared to the O-shaped dimer, S-shaped conformation results in enhanced lamellar order and reduced nonradiative recombination losses. The optimal acceptor, V-DYIC-4F, achieved a champion efficiency of 18.10% with the lowest energy loss of 0.556eV in its devices paired with PM6 due to their efficient carrier transport, and suppressed recombination compared to other devices, being attributed to the synergistic effect of conformation and end group fluorination. The insights gained in this work contribute valuable knowledge of both synthetic control and structural determination of OAs, providing strategic design guidelines for the future development of dimeric acceptors toward high-efficiency PSCs.

Assessing the economic impact of innovative cities

ABSTRACT This study examines the effects of South Korea’s Innovative City (IC) policy, which aims to redistribute public institutions to local cities to alleviate urban congestion and mitigate regional disparities. Utilizing the synthetic control method, this study evaluates the policy’s influence on local productivity and investigates its spillover effects. The findings reveal a marked increase in productivity within rural cities, highlighting the policy’s efficacy in less urbanized areas. However, the outcomes vary across different locales, with some urban ICs experiencing productivity enhancements, while rural ICs near expanding urban areas do not. Additionally, the study observes limited spillover effects in cities near ICs, indicating that indirect benefits are not uniformly distributed.

Sovereign default and FDI transactions: Evidence from Argentina

This paper investigates the effect of sovereign debt default on foreign direct investment (FDI) transactions by US firms into Argentina following the Argentine sovereign default in 2019–20. Using the synthetic control approach, we find that the number of FDI transactions decreased by approximately 60% after the Argentine default with a particularly pronounced decline in the non-manufacturing sector. By examining the changes in the number of transactions, we provide a more precise picture of the cost of sovereign default, capturing the FDI activity of small firms better.

The causal impact of a business cycle shock on road crashes and its determinants – A synthetic control group analysis

Introduction: Research suggests that recessions correlate with reductions in crash counts. However, knowledge is still scarce regarding the causality of this association, and the mechanisms through which economic shocks affect crash numbers are not well understood. We address these research gaps by applying an econometric methodology that has so far not been used for these research questions. Method: We use a quasi-natural experimental approach as our identification strategy. By exploiting the spatial heterogeneity of a shock, we define affected and less affected regions as treatment and control units. A synthetic control approach is applied to identify the causal impact of a shock on crash counts and explore the mechanisms contributing to this effect. As a case study, we use the 2008/09 financial crisis in Germany and exploit its high spatial variation. Results: We find that the crisis caused a significant crash rate reduction of 8% in the treated region. Only 1/4 of this reduction can be attributed to the decline in exposure. The remaining 3/4 are associated with the crisis-induced decrease in crash risk. Decomposing this effect shows that the crash rates in rural areas, of newly registered vehicles, of young adults, related to alcohol and speeding decline more than the overall crash rate. In contrast, crash rates of severe crashes, of heavy-goods vehicles, at night and on weekends are not the driving factors of the decrease in crash rates. Several robustness tests validate the results. Conclusions: Crash counts declined significantly due to the economic crisis. However, the magnitude of the influence is highly dependent on the crash characteristics. Practical applications: Understanding the trajectory of crash counts is crucial for implementing traffic safety measures and working towards vision zero. Our study shows that macroeconomic parameters are important potential confounding factors that should be considered in accident analysis.

Do Foreign Buyer Taxes Affect House Prices?

This paper studies the impact of foreign buyer taxes on house prices using recent law changes in Canada, Australia, and New Zealand. Counterfactual house prices are estimated for each treated location, combining prediction techniques from machine learning with inference methods from the synthetic control method literature. In general, the foreign buyer taxes we studied had negative, large, and persistent effects on house price growth. We found bigger effects in locations with higher taxes and with larger immigrant shares. Alternative outcome variables, including population growth, GDP growth, and unemployment rates, were either unaffected or slightly affected in ways that do not confound our results.

Study on the Impact of Collective Commercial Construction Land Entering the Market on Rural Residents’ Income: Taking Deqing County, Zhejiang Province as an Example

The entry of collective construction land for business purposes is an important measure for deepening the reform of the rural land system, promoting the flow of urban and rural factors, and realizing rural revitalization. Since the production of the first batch of pilot projects in 2015, 33 county-level cities have participated in the pilot policy by 2023. Deqing County, Zhejiang Province, as the first area to participate in the pilot project, aims to achieve more fruitful results. This paper first examines how promoting farmers’ income through the market entry of agricultural land can be achieved, then uses the synthetic control method to quantitatively study the impact of collective operational construction land on farmers’ income using panel data from 2011 to 2019, and finally proposes relevant suggestions from the perspective of system reform.

Firearm Purchaser Licensing Laws and Firearm Deaths Among Adolescents and Emerging Adults

Research on firearm purchaser licensing laws has found population level reductions in firearm-related mortality. Limited research has been conducted specifically examining the impact of these laws among adolescents and emerging adults. We obtained death data from the National Center for Health Statistics from 1990 to 2019. We generated state-year rates of homicide and suicide, stratified by firearm involvement, for decedents aged 15 to 24. We stratified by race and ethnicity (white, Black, and Hispanic) to assess for differential policy effects. We used stacked difference-in-difference and augmented synthetic control modeling to estimate law repeal or adoption. Repeal of firearm purchaser licensing laws was associated with significantly higher rates of firearm homicide and suicide among those age 15 to 24. The adoption of these laws was associated with significantly lower rates of firearm homicide and suicide among this group. These laws are a promising supply-side intervention to reduce firearm mortality among those with elevated violence vulnerability.

Firearm injury hospitalizations and handgun purchaser licensing laws: longitudinal evaluation of state-level purchaser licensure requirements on firearm violence, 2000–2016

BackgroundHandgun purchaser licensing (HPL) laws mandate individuals to obtain a license from law enforcement before buying a firearm. Research indicates these laws effectively reduce various forms of fatal firearm violence, including homicides, suicides, and mass shootings. Our study sought to assess the impact of HPL laws on non-fatal firearm violence.MethodsUtilizing the augmented synthetic control method (ASCM), we estimated the average treatment effect on the treated (ATT) resulting from a full repeal of an HPL law in Missouri (2007), a partial repeal in Michigan (2012), and an adoption on HPL law in Maryland (2013) on firearm injury hospitalizations. We utilized RAND's healthcare cost and utilization project-based dataset from 2000 to 2016 for our outcome variable. We conducted in-time placebo testing and leave-one-out donor pool testing as sensitivity analyses.ResultsMaryland’s adoption was associated with a statistically significant 32.3% reduction in firearm-related injury hospitalization (FIH) rates (ATT = − 0.497, standard error (SE) = 0.123); Missouri’s repeal was associated with a statistically significant 35.7% increase in FIH rates (ASCM = 0.456, SE = 0.155); and Michigan’s partial repeal showed no statistically significant associations with FIH rates (ATT = − 0.074, SE = 0.129). Sensitivity analyses confirm the robustness of the estimated HPL effects.DiscussionHPL laws appear to be protective against hospitalizations for nonfatal firearm injuries. These findings align with prior research indicating that HPL laws are effective in reducing fatal firearm violence. States without such licensing systems ought to consider these robust policies as a means to address firearm violence.