Synthetic Control Group Research Articles

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.

Implementation of integrated care for type 2 diabetes Mellitus and Periodontitis in Germany: study protocol for a practice-based and cluster-randomized trial

BackgroundType 2 Diabetes mellitus (T2DM) and periodontitis share common risk factors and influence one another. However, primary care and oral health care continue to operate separate from each other and fail to synchronize care for patients with T2DM and periodontitis. The purpose of this practice-based trial is to evaluate the implementation of a new integrated care pathway for patients with T2DM and periodontitis. The new approach integrates a screening for T2DM risk in dental care settings in patients with periodontitis, a screening for periodontitis risk in primary care settings in patients with T2DM, and mutual referrals between dentists and primary care physicians.MethodsTwo practice-based studies will be carried out in parallel: (i) In dental care settings: a practice-based, multi-centric, cluster-randomized, controlled trial with a control and an intervention group; (ii) in primary care settings: a practice-based, multi-centric, non-randomized, controlled trial with a synthetic control group calculated from claims data. Following a two-step recruitment approach, 166 dentists and 248 general practitioners will be recruited, who themselves will recruit a total of 3808 patients in their practices. Patient data will be collected at baseline, 12 months, and 24 months after study enrollment. The evaluation comprises: (i) impact evaluation, using a hierarchical linear mixed model; (ii) process evaluation, based on surveys alongside the trials; (iii) economic evaluation. In addition, a Discrete-Choice-Experiment will identify provider’s payment preferences for the new care approach.DiscussionUpon successful implementation, the intervention will enable health care providers to detect a risk for T2DM and periodontitis in patients at an early stage, thus providing patients an opportunity for timely diagnosis and therapy. Ultimately, this can lead to increased quality of life and reduced health care expenditures. On a methodologic level, the project provides novel insights into a complex intervention on the intersection of general practice and dental care.Trial registrationThe study was prospectively registered at the German Clinical Trials Register (https://drks.de/search/de/trial/DRKS00030587) on 3. July 2023 under ID “DRKS00030587“.

Revisiting corporate universities: Strategic choices shaping performance in telecom

Corporate universities (CUs) have evolved significantly over the past century, yet empirical studies examining their impact on corporate performance are notably sparse. This study addresses this gap by applying two alternative quasi-experimental designs - Propensity Score Matching (PSM) and Synthetic Control Group (SCG), to assess CU's strategic value. By examining 18 listed European telecom companies and 80 Spanish corporations across various industries during the 2004 to 2018 time span, this paper presents a comparative analysis of CU implementation effects within different corporate environments. Our findings indicate that CU establishment is a strategic choice for better corporate performance, identity, and strategy rather than an isolated educational investment. The results offer a better understanding of CU's strategic role, especially in sectors characterized by rapid technological change and the need for strategic human capital development. This study contributes to both empirical knowledge and methodology, proposing innovative ways to explore the effects of strategic decisions like CUs on corporate performance, and enhancing the dialogue between strategic human resource management and corporate investors in the scholarly and managerial domains.

Blood perfusion with polymyxin B immobilized columns in patients with COVID-19 requiring oxygen therapy

Extracorporeal blood purification with polymyxin B immobilized fiber column direct hemoperfusion (PMX-DHP), is reported to be effective in treating COVID-19 pneumonitis with oxygen demand. This multicenter prospective study evaluated the efficacy and safety of PMX-DHP in oxygen-requiring patients with COVID-19 admitted between September 28, 2020, and March 31, 2022. The primary endpoint was the percentage of clinical improvement 15 days after treatment. The secondary endpoint was the percentage of worsened disease status. Data from the COVID-19 patient registry were used for the synthetic control group. The improvement rate on Day 15 did not differ between PMX-treated patients and controls; however, the deterioration rate was 0.38 times lower in the PMX-treated group, and the death rates on Day 29 were 0 and 11.1% in the PMX-treated and control groups, respectively. The PMX group showed a 0.73 times higher likelihood for reduced intensive care demand, as 16.7% of PMX-treated patients and 22.8% of controls worsened. After treatment blood oxygenation improved, urinary β2-microglobulin and liver-type fatty acid-binding protein showed significant decreases, and IL-6 decreased once during treatment but did not persist. In this study, PMX treatment effectively prevented the worsening of COVID-19 pathology, accompanied by improved oxygenation. PMX treatment to remove activated cells may effectively improve patient outcomes.

A Comparative Evaluation of Fiscal Stabilization Strategies during the Covid-19 Pandemic with Germany as a Reference Point

Abstract We provide a comparative evaluation of fiscal stabilization strategies during the Covid-19 pandemic. For this purpose, we use Germany’s temporary value-added tax (VAT) rate reduction as a reference point. We construct a credible counterfactual for Germany in a two-step procedure. First, we carry out a careful pre-selection of the donor pool countries to obtain a control group that is highly similar to Germany regarding important post-treatment characteristics. Second, we apply a reweighting scheme on the pre-selected donor countries. The synthetic control group only differs from Germany in the way that it did not implement the temporary VAT rate reduction. Our results indicate that the German VAT cut policy and partial VAT reductions in other countries were relatively ineffective in stimulating consumption with regards to their costs when compared to other measures such as (targeted) direct cash transfers (e.g. implemented in Canada, Denmark, Japan, and the United States). We attribute this to the fact that direct cash transfers are more comprehensible, salient, and actionable, in particular, in a dynamic environment with high uncertainty induced by unclear future economic prospects.

Measuring the impact of assortment change in retail stores using the synthetic control method

This study offers an innovative method for evaluating the effects of assortment changes on retail store revenue, employing the Synthetic Control Method (SCM) with Lasso regression. In response to the limitations of randomized control trials for large-scale interventions, we propose a unique approach using Lasso regression to build synthetic control groups from comparable stores in competitor retailers. This innovative technique overcomes the obstacle of absent control data within the same retailer. Our analysis reveals a remarkable 3.7% increase in retailer revenue after implementing the assortment changes. To confirm the validity of our findings, we conducted placebo studies, solidifying the positive impact of these adjustments. These results advocate embracing the SCM with Lasso regression as a reliable tool for measuring the effects of interventions in the business world, especially when controlled experiments are not feasible. This method empowers retailers to assess the effectiveness of assortment optimization strategies and make data-driven decisions about future changes.

Direct and spillover effects of a new tramway line on the commercial vitality of peripheral streets: a synthetic-control approach

Abstract In cities, the creation of public transport infrastructure such as light rails can cause changes on a very detailed spatial scale, with different stories unfolding next to each other within the same urban neighbourhood. We study the direct effect of a light rail line built in Florence (Italy) on the retail density of the street where it was built and its spillover effect on other streets in the treated street’s neighbourhood. To this aim, we investigate the use of the synthetic control group (SCG) methods in panel comparative case studies where interference between the treated and the untreated units is plausible, an issue still little researched in the SCG methodological literature. We frame our discussion in the potential outcomes approach. Under a partial interference assumption, we formally define relevant direct and spillover causal effects.

Estimating the return on investment of the New York Tobacco Control Programme: a synthetic control study

ObjectiveTo assess the return on investment (ROI) of the New York Tobacco Control Programme (NY TCP).SettingNew York and other states of the USA.InterventionsNY TCP.OutcomesSmoking prevalence, smoking-attributable healthcare expenditures (SAEs), smoking-attributable...

The impact of devolution on local health systems: Evidence from Greater Manchester, England

Devolution and decentralisation policies involving health and other government sectors have been promoted with a view to improve efficiency and equity in local service provision. Evaluations of these reforms have focused on specific health or care measures, but little is known about their full impact on local health systems. We evaluated the impact of devolution in Greater Manchester (England) on multiple outcomes using a whole system approach.We estimated the impact of devolution until February 2020 on 98 measures of health system performance, using the generalised synthetic control method and adjusting for multiple hypothesis testing. We selected measures from existing monitoring frameworks to populate the WHO Health System Performance Assessment framework. The included measures captured information on health system functions, intermediatory objectives, final goals, and social determinants of health. We identified which indicators were targeted in response to devolution from an analysis of 170 health policy intervention documents.Life expectancy (0.233 years, S.E. 0.012) and healthy life expectancy (0.603 years, S.E. 0.391) increased more in GM than in the estimated synthetic control group following devolution. These increases were driven by improvements in public health, primary care, hospital, and adult social care services as well as factors associated with social determinants of health, including a reduction in alcohol-related admissions (−110.1 admission per 100,000, S.E. 9.07). In contrast, the impact on outpatient, mental health, maternity, and dental services was mixed.Devolution was associated with improved population health, driven by improvements in health services and wider social determinants of health. These changes occurred despite limited devolved powers over health service resources suggesting that other mechanisms played an important role, including the allocation of sustainability and transformation funding and the alignment of decision-making across health, social care, and wider public services in the region.

Impact of Total Indoor Smoking Ban on Cardiovascular Disease Hospitalizations and Mortality: The Case of Chile.

The harmful effects of first and secondhand smoking are well-established. Smoke-free laws aim at protecting nonsmokers. This study aimed to assess the impact of the 2013 total ban on indoor smoking in Chile on hospitalizations and deaths of major cardiovascular events. The logarithm of the monthly hospitalization and death rates, standardized by age for every 100 000 inhabitants, were estimated for ischemic heart disease, acute myocardial infarction, strokes, and a composite outcome of ischemic heart diseases (which includes acute myocardial infarction) and strokes. In addition, interrupted time series with synthetic control groups were used to assess changes in levels and trends after the intervention. The total ban on indoor smoking caused significant reductions in death rates for the three diseases studied for age groups above 20 years old. In addition, there were substantial decreases in the post-intervention hospitalization rates for ischemic heart disease: for the 20-44 age group, the decrease was 8.7% compared to the pre-intervention period (p < .01). In comparison, such a reduction was 4% (p < .01) for the ≥65 age group. For acute myocardial infarction, the decrease was 11.5% (p < .01) for the 20-44 age group, while for stroke, it was a 1.2% (p < .01) decrease for the total population. It is estimated that the smoking ban averted 15.6% of the deaths compared with the synthetic control groups. The implementation of total smoke-free environments in Chile contributed to the reduction of mortality for main cardiovascular diseases. This study provides additional evidence of causality linking the policy to health outcomes. The total indoor smoking ban significantly affected age-standardized hospitalization and deaths. The number of deaths averted by this policy is estimated at approximately 4758 and 5256 for IHD and stroke, respectively, during the 2013-2017 period (15.6% fewer deaths than predicted by the synthetic control groups). The study contributes to the body of evidence that supports total indoor smoking bans.

Оценка влияния экономических санкций на российскую экономику с применением метода синтетической контрольной группы

The research deals with the synthetic control group method application to assess the causal effect of economic sanctions on the Russian economy. The analysis of SCG method assumptions to the problem allowed us to establish that the most problematic issue is comparison group formation. We use the source data from the World Development Indicators database. GDP by PPP per capita was an outcome variable. The application of the method to assessing the impact of sanctions pressure shows that it is possible to select the weights in such a way as to ensure good closeness of the indicators of real and synthetic Russia in the pre-event period. Such states as Kazakhstan, Argentina, Brazil, and the USA were most in demand for the formation of a synthetic Russia. However, the estimates are unstable to changes in the set of countries used to form the synthetic control.

The effect of the implementation of the international code of marketing of breast-milk substitutes on child mortality in Ghana and Tanzania.

The International Code of Marketing of Breast-Milk Substitutes is an important instrument to protect and promote appropriate infant and young child feeding and the safe use of commercial milk formulas. Ghana and Tanzania implemented the Code into national legislation in 2000 and 1994, respectively. We aimed to estimate the effects of the Code implementation on child mortality (CM) in both countries. The countries analysed were Ghana and Tanzania. For CM and HIV rates, data from the Institute for Health Metrics and Evaluation from up to 2019 were used. Data for income and skilled birth rates were retrieved from the World Bank, for fertility from the World Population Prospects, for vaccination from the Global Health Observatory and for employment from the International Labour Organization. We used the synthetic control group method and performed placebo tests to assess statistical inference. The primary outcomes were CM by lower respiratory infections, mainly pneumonia, and diarrhoea and the secondary outcome was overall CM. One-sided inference tests showed statistically significant treatment effects for child deaths by lower respiratory infections in Ghana (P = 0·0476) and Tanzania (P = 0·0476) and for diarrhoea in Tanzania (P = 0·0476). More restrictive two-sided inference tests showed a statistically significant treatment effect for child deaths by lower respiratory infections in Ghana (P = 0·0476). No statistically significant results were found for overall CM. The results suggest that the implementation of the Code in both countries had a potentially beneficial effect on CM due to infectious diseases; however, further research is needed to corroborate these findings.

Comparative effectiveness of tocilizumab vs standard care in patients with severe COVID-19-related pneumonia: a retrospective cohort study utilizing registry data as a synthetic control

BackgroundThe severity of coronavirus disease 2019 (COVID-19) infections has led to the development of several therapeutic agents, with tocilizumab becoming increasingly used to treat patients with COVID-19-related pneumonia. This study compared the use of tocilizumab treatment with the standard of care (SOC) to determine its efficacy against severe COVID-19-related pneumonia in Japan.MethodsThis retrospective cohort study was designed to evaluate the efficacy of tocilizumab in two different databases: the JA42434 single-arm study and COVID-19 Registry Japan (COVIREGI-JP), with a synthetic control group from the COVIREGI-JP cohort as a benchmark for the tocilizumab group. The study’s primary objective was to evaluate the efficacy of tocilizumab in treating severe COVID-19-related pneumonia compared to the SOC among patients included in the above two databases. The SOC group was extracted as the synthetic control group using exact matching and a propensity score matching in sequence per subject. As a secondary objective, the efficacy of tocilizumab compared to the SOC was evaluated exclusively among patients included in the COVIREGI-JP database. In each objective, the primary endpoint was defined as the time to discharge or the status of awaiting discharge.ResultsFor the primary endpoint, the hazard ratio (HR) of the tocilizumab group against the SOC group was 1.070 (95% confidence interval [CI]: 0.565–2.028). The median time from Study Day 1 to discharge or the state of awaiting discharge was 15 days in the tocilizumab group and 16 days in the SOC group. The HRs for the secondary endpoints, namely, time to improvement in the clinical state, time to clinical failure, and time to recovery, were 1.112 (95% CI: 0.596–2.075), 0.628 (95% CI: 0.202–1.953), and 1.019 (95% CI: 0.555–1.871), respectively. Similarly, the HR of the primary endpoint for the secondary objective was 0.846 (95% CI: 0.582–1.230).ConclusionsTocilizumab did not demonstrate a positive effect on time to discharge or the state of awaiting discharge. Furthermore, no statistically significant differences in other clinical outcomes, such as time to improvement in the clinical state, time to clinical failure, and time to recovery, were observed among the groups.

Has the opening of Amazon fulfillment centers affected demand for disability insurance?

An estimated 17.6% of blue-collar, manufacturing jobs were lost in the United States between 1970 and 2016. These jobs, often union-represented, provided relatively generous pay and benefits, creating a path to the middle class for individuals without a four-year college degree. Evidence suggests the closure of manufacturing facilities and resulting decline in economic opportunity increased demand for disability insurance (SSDI) among blue-collar workers. In recent years, the opening of Amazon Fulfillment Centers (FCs) has accelerated around the country, driving a wave of blue-collar job creation. We estimated the extent to which the opening of FCs affected SSDI application rates, including rates of approvals and denials, using a synthetic control group approach. We found that FC openings were associated with a 1.4% reduction in the SSDI application rate over the subsequent three years, translating to 5,528 fewer applications per year across commuting zones with an FC opening. Our findings are consistent with FC openings improving economic opportunities in local labor markets, though our confidence intervals were wide and included the null.

The impact of the international code of marketing of breast-milk substitutes in Ghana and Tanzania

Abstract Background Measures that promote and protect breastfeeding have a major impact on child survival rates, as it was estimated that increasing breastfeeding rates can reduce child mortality by 13% in Africa. The International Code of Marketing of Breast-Milk Substitutes is an important measure to protect and promote breastfeeding and the safe use of commercial milk formulas. Ghana and Tanzania adopted measures that are substantially aligned with the Code into national legislation in 2000 and 1994, respectively. Methods In this study, we estimate the effects of the Code implementation through national laws on child mortality in Ghana and Tanzania by using the synthetic control group method and performing placebo tests to assess statistical inference. The main outcome is the effect of the national laws on overall child mortality and secondary outcomes are the effect of the laws on child mortality by lower respiratory infections and diarrhea in both countries. Results Two-sided inference tests showed a statistically significant treatment effect for deaths by lower respiratory infections in Ghana (p = 0.0476; LTE = - 0.8423) and one-sided inference tests showed statistically significant treatment effects for deaths by lower respiratory infections in Ghana (p = 0.0476; LTE = -0.8423) and Tanzania (p = 0.0476; LTE = - 5.1627), and for diarrhea in Tanzania (p = 0.0476; LTE = - 8.1694). To corroborate our results, we also performed the analysis for two major causes of child mortality that are not affected by the intervention, namely congenital diseases and birth asphyxia and trauma birth, for which we did not find significant treatment effects. Conclusions The results demonstrate that the Code had a potentially beneficial impact on child mortality in Ghana and Tanzania and corroborate previous research that the Code is a necessary but insufficient step to alone improve child health outcomes. Key messages • The results show that the implementation of the Code had a potentially beneficial impact on child mortality in Ghana and Tanzania. • Policymakers should consider implementing or strengthening the Code within countries in order to improve child and health outcomes.

Evaluating the impact of using mobile vaccination units to increase COVID-19 vaccination uptake in Cheshire and Merseyside, UK: a synthetic control analysis

ObjectiveTo evaluate the impact of mobile vaccination units on COVID-19 vaccine uptake of the first dose, the percentage of vaccinated people among the total eligible population. We further investigate whether...

The effects of increased monitoring on high wealth individuals: Evidence from a quasi-natural experiment in Indonesia

In 2009, Indonesia introduced a specialised tax office focused on High Wealth Individuals (HWIs), increasing the audit probability and monitoring of around 1200 wealthy taxpayers in Jakarta. Leveraging a quasi-natural experiment and analysing 141,097 de-identified individual tax return records between 2006 and 2012, we developed a set of counterfactuals to evaluate the post- and pre-treatment tax declarations of the monitored taxpayers relative to their synthetic control groups. Our results indicate that although post-treatment declaration of taxable and earned income, as well as income tax, increased, the effect was short-lived. The increase in reported earned income was larger relative to taxable income, suggesting that monitored individuals exerted efforts to reduce tax payments. Furthermore, we identified a comparable positive spillover effect on income declaration for non-treated taxpayers in Jakarta who met the HWI criteria. We also demonstrated that the spillover effect drastically decreased as financial characteristics (such as income and wealth) diverged from those of the targeted population. Overall, the additional tax revenue generated from this program is small in comparison to the total tax revenue collected.

The impact of computing infrastructure on carbon emissions: an empirical study based on china national supercomputing center

Digitalization is viewed as a potential solution to environmental sustainability issues. However, existing researches suggest that the environmental impact of digital technology is uncertain. This study focuses on the National Supercomputing Center (NSC) in China, a large-scale computing infrastructure, and expands the correlation between digital infrastructure and green development from a computing perspective. Based on the synthetic control method, we select non-supercomputing cities as the control group and assign appropriate weighting. Through the fitting of a synthetic control group (refer to as the synthetic city) with similar characteristics, the analysis is conducted to compare carbon emissions (CO2 emission) between NSC city and the synthetic city. The empirical results show that the NSC may worsen regional CO2 emissions, and this result still holds true after a series of robustness tests. Mechanism examinations show that the NSC does not exhibit significant composition effect (energy structure improvement) and technology effect (green technology innovation), while scale effect (increase in energy demand and consumption) dominate the NSC’s carbon emissions. Based on these findings, we consider that in addition to improving the energy efficiency of supercomputing centers, the adoption of cleaner renewable energy and the promotion of knowledge spillovers are crucial for achieving a green transformation for computing infrastructure.

The COVID-19 Pandemic, Prison Downsizing, and Crime Trends

California has fundamentally reformed its criminal justice system. Since 2011, the state passed several reforms which reduced its massive prison population. Importantly, this decarceration has not harmed public safety as research finds these measures had no impact on violent crime and only marginal impacts on property crime statewide. The COVID-19 pandemic furthered the state’s trend in decarceration, as California reduced prison and jail populations to slow the spread of the virus. In fact, in terms of month-to-month proportionate changes in the state correctional population, California’s efforts to reduce overcrowding as a means to limit the spread of COVID-19 reduced the correctional population more severely and abruptly than any of the state’s decarceration reforms. Although research suggests the criminal justice reforms did not threaten public safety, there is reason to suspect COVID-mitigation releases did. How are COVID-19 jail downsizing measures and crime trends related in California, if at all? We address this question in the current study. We employ a synthetic control group design to estimate the impact of jail decarceration intended to mitigate COVID-19 spread on crime in California’s 58 counties. Adapting the traditional method to account for the “fuzzy-ness” of the intervention, we utilize natural variation among counties to isolate decarceration’s impact on crime from various other shocks affecting California as a whole. Findings do not suggest a consistent relationship between COVID-19 jail decarceration and violent or property crime at the county level.

Estimating pass-through rates for the 2022 tax reduction on fuel prices in Germany

We analyze the effectiveness of the German tax reduction on fuel prices (‘Tankrabatt’) that was introduced for three months, starting on 1 June 2022. We use the synthetic difference-in-differences estimator to compare actual retail prices of gasoline and diesel to those in a counterfactual situation without the tax reduction. For gasoline, we find that the tax reduction has been completely passed on to consumers. This result is robust to different approaches of constructing the synthetic control group. For diesel, we find evidence of at least partial pass-through, although the estimates are more sensitive to the employed specification. Moreover, the evidence suggests that pass-through rates for diesel started to decline in August while the tax reduction was still in place.