Spatial Seemingly Unrelated Regression Models for Freight Trip Generation by Vehicle Type: Application to the Chennai Metropolitan Area in India

During the last two decades, there has been substantial interest in developing freight trip generation (FTG) models. Most studies consider only truck trips or convert all freight trips into equivalent truck trips. Freight in several large cities is increasingly being moved by smaller vehicles. This calls for modeling FTG by vehicle type. The present research identifies and compares establishment characteristics affecting FTG by different vehicle types. In this context, spatial correlations among nearby establishments and the error-term correlations between independent models by vehicle type become relevant. Based on the Lagrange-Multiplier (LM) tests, we develop non-spatial seemingly unrelated regression (SUR) models for freight trip production (FTP) and spatial SUR models with a spatial lag in the dependent variable to account for both spatial and error-term correlations for freight trip attraction (FTA). The results show that establishment type and size affect FTG by different vehicle types.

Human capital and economic growth in Nigeria

The study empirically examines the nexus between human capital and economic growth in Nigeria between 1981 and 2017. This is predated by poor policy impact across the key sectors of the economy, such as education and health that would have transformed productivity to economic in Nigeria. In order to address this ugly happening, the study therefore employed vector autoregressive and Johansen techniques. The results disclosed that the estimated coefficients of human capital have long-run significant impact on economic growth in Nigeria. Also, the diagnostic tests were used to check the validity of the techniques adopted in the study. Interestingly, results from normality test, VEC residual serial correlation LM tests and VEC residual heteroskedasticity tests confirm the justification and validity of the estimated results obtained in this research. Drawing way forward, this study therefore recommends the need to sustain economic in Nigeria through increase budgetary allocation to education and health sector to boost human capital skills needed to drive knowledge-based economy. Also, government should establish special agencies with the responsibility of improving the skills and capabilities of human capital across all educational levels of the federation so as to sustain growth in the long run.

Preliminary test almost unbiased ridge estimator in a linear regression model with multivariate Student-t errors

In this paper, the preliminary test almost unbiased ridge estimators of the regression coefficients based on the conflicting Wald (W), Likelihood ratio (LR) and Lagrangian multiplier (LM) tests in a multiple regression model with multivariate Student-t errors are introduced when it is suspected that the regression coefficients may be restricted to a subspace. The bias and quadratic risks of the proposed estimators are derived and compared. Sufficient conditions on the departure parameter ∆ and the ridge parameter k are derived for the proposed estimators to be superior to the almost unbiased ridge estimator, restricted almost unbiased ridge estimator and preliminary test estimator. Furthermore, some graphical results are provided to illustrate theoretical results.

Implications of shocks in energy consumption for energy policy in sub-Saharan Africa

Sub-Saharan Africa has the lowest energy consumption per capita in the world, and this has undermined socioeconomic development in the region. The stationarity of energy consumption in the region has important implications for energy policy, forecasting and macroeconomic developments. This paper investigates the stationarity properties of energy consumption in 48 sub-Saharan Africa countries using the Augment Dickey–Fuller, Zivot–Andrews, Clemente–Montanes–Reyes and Lee–Strazicich LM tests. Using the Lee-Strazicich LM test as a benchmark, the study shows that energy consumption is stationary in 41 countries. This implies that energy policy makers should not be concerned about shocks in energy consumption in these countries because the shocks will be temporary and not transmitted to the macroeconomy. Also, energy policies will not have long-term effects. Policies that exert one-time temporary shocks on energy consumption would be more effective in these countries.

Bootstrap LM Tests for Spatial Dependence in Panel Data Models with Fixed Effects

This paper applies bootstrap methods to LM tests (including LM-lag test and LM-error test) for spatial dependence in panel data models with fixed effects, and removes fixed effects based on orthogonal transformation method proposed by Lee and Yu (2010). The consistencies of LM tests and their bootstrap versions are proved, and then some asymptotic refinements of bootstrap LM tests are obtained. It shows that the convergence rate of bootstrap LM tests is O((NT)−2) and that of fast double bootstrap LM tests is O((NT)−5/2). Extensive Monte Carlo experiments suggest that, compared to aysmptotic LM tests, the size of bootstrap LM tests gets closer to the nominal level of signifiance, and the power of bootstrap LM tests is higher, especially in the cases with small spatial correlation. Moreover, when the error is not normal or with heteroskedastic, asymptotic LM tests suffer from severe size distortion, but the size of bootstrap LM tests is close to the nominal significance level. Bootstrap LM tests are superior to aysmptotic LM tests in terms of size and power.

Intestinal Permeability and Inflammation Mediate Dietary Intake Associated Risks of Micronutrient Deficiencies at 15 Months: Results from the MAL-ED Study (OR07-04-19)

Objectives We tested whether environmental enteric dysfunction (EED) is associated with risk of micronutrient deficiencies adjusting for diet and systemic inflammation, and whether it mediates the relation between intake and micronutrient status. Methods Data from 1283 children in the MAL-ED birth cohort were examined to evaluate risk of anemia, low plasma retinol, zinc, and ferritin, and high plasma transferrin receptor (TfR) at 15 months. We characterized gut inflammation and permeability by myeloperoxidase, neopterin, and alpha-1-antitrypsin concentrations from monthly asymptomatic fecal samples averaged from 9–15 months, and urinary recovery of lactulose (L) and mannitol (M) from LM tests at 9 and 15 months, converted to a ratio z score (LMZ) and averaged. Nutrient intakes from complementary foods were quantified monthly from 9–15 months and densities were averaged. Plasma alpha-1 acid glycoprotein at 15 months characterized systemic inflammation. Relationships among variables were modelled using a direct acyclic graph. Results Greater risk of anemia was associated with permeability [LMZ: 1.15 (95% confidence interval: 1.01–1.31)] and inflammation [myeloperoxidase: 1.16 (1.01–1.34)]. Greater risk of low ferritin was associated with alpha-1-antitrypsin [1.19 (1.03–1.37)] and neopterin [1.22 (1.04–1.43)]. Greater risk of low retinol was associated with LMZ [1.25 (1.07–1.45)]. However, myeloperoxidase was associated with lower risk of high TfR [0.86 (0.74–0.98)], neopterin with lower risk of low retinol [0.75 (0.62–0.89)], and alpha-1-antripysin with lower risk of low plasma zinc [0.83 (0.70–0.99)]. Greater nutrient densities of vitamin A, B6, calcium, protein and zinc were negatively associated with EED. Inverse associations between nutrient densities and micronutrient deficiency largely disappeared after adjustment for EED, suggesting that EED mediates associations between intake and status. Conclusions EED is independently associated with increased risk of low ferritin, low retinol and anemia. Greater nutrient density from complementary foods may reduce EED, and control of micronutrient deficiency may require control of EED. Funding Sources The MAL-ED study was supported by the Bill & Melinda Gates Foundation, through awards to the Foundation for the NIH and NIH/FIC.