Search Results (9)

This paper introduces a rank-based panel kink threshold regression model with a covariate-dependent threshold, where the threshold is specified as a function of informative covariates. To estimate the model parameters, we propose a profile estimation procedure for both the threshold parameters and regression coefficients. Additionally, we develop a Wald test statistic to examine the constancy of the threshold and a sup-score test to detect the presence of the kink effect. Through simulation studies and an empirical analysis, we demonstrate that the proposed methods exhibit robustness against outliers and heavy-tailed errors in both parameter estimation and hypothesis testing. Full article

This study examines whether the relationship between provincial fiscal revenue and expenditure measures and grain production in China is nonlinear. Using a balanced panel of 31 provinces from 2007 to 2021, we analyze major revenue-side and expenditure-side fiscal instruments, including the cultivated land occupation tax, value-added tax, agricultural insurance subsidies, agricultural loan interest subsidies, rural minimum living security subsidies, education expenditure, and transportation infrastructure expenditure. To identify regime-dependent changes in estimated associations, we employ panel kink and double-kink regression models with endogenously estimated kink points. The results suggest that the estimated relationships are intensity-dependent rather than constant. The cultivated land occupation tax exhibits a kinked relationship with grain production, with a more positive association beyond a certain level. Agricultural insurance subsidies display a double-kink pattern, with the strongest positive estimated association concentrated in an intermediate range of the subsidy measure. Rural minimum living security subsidies are positively associated with grain production at lower levels, but this association weakens and may become negative after the estimated kink point. Overall, the findings suggest that the relationship between fiscal variables and grain production depends not only on policy direction but also on the levels of the fiscal measures. Full article

Background: Intentional occlusion of the internal iliac artery (IIA) during endovascular repair of aorto-iliac aneurysms may predispose patients to pelvic ischemic complications such as gluteal claudication, erectile dysfunction, and bowel ischemia. Iliac branch devices (IBDs) have been developed to preserve hypogastric perfusion. E-Liac (Artivion/Jotec) is one of the latest modular IBDs yet reports on mid-term performance are limited to small single-center cohorts with short follow-up. The CAMpania PugliA bRanch IliaC (CAMPARI) study is a multicenter investigation of E-Liac outcomes. Methods: A retrospective observational cohort study was conducted across five Italian vascular centers. All consecutive patients undergoing E-Liac implantation for aorto-iliac or isolated iliac aneurysms between January 2015 and December 2024 were identified from prospectively maintained registries. Inclusion criteria comprised elective or urgent endovascular repair of aorto-iliac aneurysms in which an adequate distal sealing zone was not available without covering the IIA and suitability for the E-Liac device according to its instructions for use (IFU). Patients with a life expectancy < 1 year or hostile anatomy incompatible with the IFU were excluded. The primary end point was freedom from branch instability (occlusion/stenosis, kinking, or detachment of the bridging stent). Secondary end points included freedom from any endoleak, freedom from device-related reintervention, freedom from gluteal claudication, aneurysm-related and all-cause mortality, acute renal failure, and sac regression > 5 mm. Results: A total of 69 consecutive patients (68 male, 1 female, median age 72.0 years) received 74 E-Liac devices, including 5 bilateral implantations. The mean infrarenal aortic diameter was 45 mm and the mean CIA diameter 34 mm; 14 patients (20.0%) had a concomitant IIA aneurysm (>20 mm). Concomitant fenestrated or branched aortic repair was performed in 23% of procedures. Two patients received a standalone IBD without implantation of a proximal aortic endograft. Technical success was achieved in 71/74 cases (96.0%); three failures occurred due to inability to catheterize the IIA. Distal landing was in the main IIA trunk in 58 cases and in the posterior branch in 13 cases. Over a median follow-up of 18 (6; 36) months, there were four branch instability events (5.4%): three occlusions and one bridging stent detachment. Seven patients (9.5%) developed endoleaks (one type Ib, two type II, two type IIIa, and two type IIIc). Five patients (6.8%) required reintervention, and five (6.8%) reported gluteal claudication. There were seven all-cause deaths (10%), none within 30 days or related to aneurysm rupture; causes included COVID-19 pneumonia, acute coronary syndrome, melanoma, gastric cancer, and stroke. No acute renal or respiratory failure occurred. Kaplan–Meier analysis showed 92% (95% CI 77–100) freedom from branch instability in the main-trunk group and 89% (60–100) in the posterior-branch group (log-rank p = 0.69). Freedom from any endoleak at 48 months was 87% (95% CI 75–95), and freedom from reintervention was 93% (95% CI 83–98). Conclusions: In this multicenter cohort, the E-Liac branched endograft demonstrated high technical success and favorable early–mid-term outcomes. Preservation of hypogastric perfusion using E-Liac was associated with low rates of branch instability, endoleak, and reintervention, with no 30-day mortality or aneurysm-related deaths. These findings support the safety and efficacy of E-Liac for aorto-iliac aneurysm management, although larger prospective studies with longer follow-up are needed. Full article

This paper investigates the relationship between public debt and economic growth in the context of a panel kink regression with latent group structures. The proposed model allows us to explore the heterogeneous threshold effects of public debt on economic growth based on unknown group patterns. We propose a least squares estimator and demonstrate the consistency of estimating group structures. The finite sample performance of the proposed estimator is evaluated by simulations. Our findings reveal that the nonlinear relationship between public debt and economic growth is characterized by a heterogeneous threshold level, which varies among different groups, and highlight that the mixed results found in previous studies may stem from the assumption of a homogeneous threshold effect. Full article

This study aims to accomplish three main tasks. Firstly, it seeks to determine the more appropriate choice between classical and Bayesian methods in estimating a pooled panel kink regression model under the condition of a known but bounded policy variable choice that serves as a kink point. Secondly, as a product of the first target, the study seeks to provide empirical evidence for the economic growth–economic freedom nexus in five top-performing economies in Sub-Saharan Africa. Using index explanatory variables, which are bounded between 0 and 100, and using both numerical and graphical methods, the findings show that the use of the Bayesian method is more appropriate in characterizing the data than the classical OLS framework, as the former better accounts for randomness via the use of posterior distributions. Finally, the study further employed both threshold and Bayesian pooled panel kink regressions, with mixed results. The Bai–Perron test confirmed that the economic freedom index has a single threshold value of 56.70. Whereas the threshold estimates show a negative impact of economic freedom on growth in both low and high regimes, the Bayesian estimates reveal that economic freedom has a negative impact on growth in a low regime but a positive impact in a high regime. Our novel findings show that there exists a nonlinear impact of economic freedom on growth. This provides some guidance and caution in charting policy paths that seek to achieve economic growth. Full article

More countries have made carbon neutral or net zero emission commitments since 2019. Within this context, re-examining the environmental Kuznets curve (EKC) hypothesis plays an essential role in sizing up the global economic development situation and realizing the global carbon emission reduction target. A methodological challenge in testing the EKC hypothesis, which states that increasing income makes CO₂ emissions begin to decline beyond a turning point, lies in determining if this benchmark point exists. The EKC hypothesis between income and CO₂ emissions is reassessed by applying a new kink regression model for the G7 countries from 1890 to 2015. Results reveal the inverted U-shaped nexus does not exist for US, Germany, Italy, Canada and Japan. For these five countries, the EKC curve has a turning point, but the positive impact of incomes on CO₂ emissions becomes significantly smaller after the turning point. We describe this relationship as a pseudo-EKC. K.U.K. and France are the only exceptions, fitting the EKC hypothesis. Further analysis indicates that the relationship between income and SO₂ emissions presents an inverted U-shaped curve. Moreover, we observe that the turning point occurs at different points in time for the different G7 countries. Therefore, environmental policies targeting pollutant emission reduction should consider the different characteristics of different pollutants and regions. Full article

This study examines the nonlinear impact of tourism development on economic growth in Southeast Asian countries using the panel kink regression model. Due to the paucity of Southeast Asian data, we may face the overparameterization problem in our model. To deal with this problem, this study proposes the Generalized Maximum Entropy (GME) estimator to estimate the unknown parameters in this nonlinear model. Several important tourism development indicators consisting of the total international arrivals, international tourism expenditure, and tourism receipts are considered. In addition, we also consider the gross capital formation and real effective exchange rate as a control variable in our nonlinear model. Our findings show that the effect of international tourist arrivals on economic growth should be separated into two regimes, while other factors do not exhibit a nonlinear relationship with Southeast Asian economic growth. Thus, we construct the empirical model with the kink effect in the variable of international tourist arrivals. To confirm the performance of the GME estimator, we compare it to the ordinary least squares and the fixed effect estimators. According to the mean squared and root means squared errors, we find that our GME estimator performs better than the ordinary least squares and the fixed effect estimators. This indicates that GME estimation is an applicable method for estimating the nonlinear effect of tourism growth on economic growth. Our empirical results show that there are positive impacts of tourism growth on economic growth for regime 1 (low tourism demand) and regime 2 (high tourism demand) with the effect of the low tourist arrivals regime being relatively larger. We also find a positive influence of gross capital formation, real effective exchange rate, international tourism expenditure, and tourism receipts on Southeast Asian economic growth. Full article

This study analyzed the nonlinear impacts of education, particularly higher education, on economic growth in the ASEAN-5 countries (i.e., Thailand, Indonesia, Malaysia, Singapore, and the Philippines) over the period 2000–2018. The impacts of education on economic growth are assessed through various education indicators, consisting of public expenditure on tertiary education per student, enrolment rates of primary, secondary, and tertiary levels, educated workforce, and the novel indicator of unemployment rates with advanced education. This study establishes nonlinear regression models—the time-series kink regression and the panel kink regression—to investigate the kink effects of education on the individual country’s economic growth and the ASEAN-5 region, respectively. There are three main findings. Firstly, the nonlinear effects of the government expenditure per tertiary student on economic growth are confirmed for the ASEAN-5 region. However, the impacts do not follow the law of diminishing returns. Secondly, our findings reveal that an increase in unemployment of advanced educated workers can positively or negatively impact economic growth, which requires an appropriate policy to handle the negative impacts. Lastly, secondary and higher education enrollment rates can contribute to the ASEAN-5’s economic growth (both the individual and regional levels). However, the regional analysis reveals that higher education impacts become twice as strong when the enrollment rates are greater than a certain level (a kink point). Therefore, we may conclude that secondary enrollment rates positively affect economic growth; however, higher education is the key to future growth and sustainability. Full article

This study aims to examine the relationship between economic development and environmental degradation based on the Environmental Kuznets Curve (EKC) hypothesis. The level of CO₂ emissions is used as the indicator of environmental damage to determine whether or not greater economic growth can lower environmental degradation under the EKC hypothesis. The investigation was performed on eight major international economic communities covering 44 countries across the world. The relationship between economic growth and environmental condition was estimated using the kink regression model, which identifies the turning point of the change in the relationship. The findings indicate that the EKC hypothesis is valid in only three out of the eight international economic communities, namely the European Union (EU), Organization for Economic Co-operation and Development (OECD), and Group of Seven (G7). In addition, interesting results were obtained from the inclusion of four other control variables into the estimation model for groups of countries to explain the impact on environmental quality. Financial development (FIN), the industrial sector (IND), and urbanization (URB) were found to lead to increasing CO₂ emissions, while renewable energies (RNE) appeared to reduce the environmental degradation. In addition, when we further investigated the existence of the EKC hypothesis in an individual country, the results showed that the EKC hypothesis is valid in only 9 out of the 44 individual countries. Full article