Robust Small Sample Accurate Inference in Moment Condition Models

Procedures based on the Generalized Method of Moments (GMM) (Hansen, 1982) are basic tools in modern econometrics. In most cases, the theory available for making inference with these procedures is based on first order asymptotic theory. It is well-known that the (first order) asymptotic distribution does not provide accurate p-values and confidence intervals in moderate to small samples. Moreover, in the presence of small deviations from the assumed model, p-values and confidence intervals based on classical GMM procedures can be drastically affected (nonrobustness). Several alternative techniques have been proposed in the literature to improve the accuracy of GMM procedures. These alternatives address either the first order accuracy of the approximations (information and entropy econometrics (IEE)) or the nonrobustness (Robust GMM estimators and tests). In this paper, we propose a new alternative procedure which combines robustness properties and accuracy in small samples. Specifically, we combine IEE techniques as developed in Imbens, Spady, Johnson (1998) to obtain finite sample accuracy with robust methods obtained by bounding the original orthogonality function as proposed in Ronchetti and Trojani (2001). This leads to new robust estimators and tests in moment condition models with excellent finite sample accuracy. Finally, we illustrate the accuracy of the new statistic by means of some simulations for three models on overidentifying moment conditions.Exponential tilting, Generalized method of moments, Information and entropy econometrics, Monte Carlo, Robust tests, Saddlepoint techniques

IDE, FINANCE ET CROISSANCE ECONOMIQUE EN AFRIQUE SUBSAHARIENNE

This paper examines the role of the financial sector in the relationship between FDI and economic growth in Sub-Saharan Africa. We use panel data from 24 African countries over the period 1996-2014. The results obtained with the application of quantitative regression on instrumental variables, taking into account country fixed effects, show that financial development measured by bank credit improves the contribution of FDI to growth. This result is more significant in countries that are in the lower quantiles following the conditional distribution of per capita income. However, finance is not significant as a channel of transmission of FDI on growth when measured by a multi-dimensional index.  Based on this finding, the study recommends rethinking FDI promotion policies in Africa by articulating them in a coherent manner with financial sector support policies

Développement financier et transformation structurelle des pays africains de la zone Franc : une approche panel-VAR

The African countries of the Franc Zone are on the margin of the observed industrialization process in several developing countries around the world. This research examines the relationship between the development of the financial sector and the industrialization of African economies in the Franc Zone. A vector auto regressive model (VAR) with errors corrections is used in order to better determine the effects of a financial innovation on industrialization over time. The results show that a shock on bank credit allocated to the private sector has a negative short-term and a positive long-term effect on the manufacturing sector. This negative effect takes longer before easing in the CAEMC (CEMAC) zone compared to the WAEMU (UEMOA) zone. Moreover, the dynamics of the manufacturing sector remains insensitive to the shocks on the monetary aggregate M2 and the inflation.Les pays africains de la zone Franc sont à la marge du processus d’industrialisation observé dans plusieurs pays en développement dans le monde. Cette recherche examine la relation entre le développement du secteur financier et l’industrialisation des économies africaines de la zone Franc. Nous utilisons un modèle vectoriel autorégressif (VAR) à correction d’erreurs afin de mieux cerner les effets d'une innovation financière sur l'industrialisation dans la durée. Les résultats montrent qu’un choc sur les crédits bancaires alloués au secteur privé produit un effet négatif à court terme et positif à long terme sur le secteur manufacturier. Cet effet négatif met plus de temps avant de s’atténuer dans la Zone CEMAC en comparaison avec la Zone UEMOA. De plus, la dynamique du secteur manufacturier reste insensible aux chocs sur l’agrégat monétaire M2 et l'inflation

The prognostic value of tumor mitotic rate in children and adolescents with cutaneous melanoma:A retrospective cohort study

Background: Mitotic rate is a strong predictor of outcome in adult patients with primary cutaneous melanoma, but for children and adolescent patients this is unknown. Objective: We sought to assess the prognostic value of primary tumor mitotic rate in children and adolescents with primary melanoma. Methods: This was a cohort study of 156 patients who were <20 years of age and who had clinically localized cutaneous melanoma. Patients <12 years of age were classified as children and those 12 to 19 years of age as adolescents. Clinicopathologic and outcome data were collected. Recurrence-free and melanoma-specific survival were calculated. Univariable and multivariable analyses were performed using Cox proportional hazard models. Results: Thirteen of 156 patients (8%) were children. The mitotic rate was ≥1/mm2 in 104 patients (67%) and correlated with increasing Breslow thickness. A positive sentinel node was found in 23 of 61 patients (38%) in whom a sentinel lymph node biopsy specimen was obtained. The median follow-up was 61 months. Five-year melanoma-specific and recurrence-free survival rates were 91% and 84%, respectively. Mitotic rate was a stronger predictor of outcome than tumor thickness and was the only factor independently associated with recurrence-free survival. Limitations: This research was conducted at a single institution and the sample size was small. Conclusion: Mitotic rate is an independent predictor of recurrence-free survival in children and adolescents with clinically localized melanoma

Development and evaluation of an on-ride motorcycle coaching program in Victoria: how well was VicRide implemented and received by the target novice motorcycle riders?

VicRoads initiated a large-scale trial of a newly developed &lsquo;VicRide on-road coaching program&rsquo; forrecently licensed motorcyclists in Victoria. The George Institute for Global Health wascommissioned to evaluate VicRide primarily to determine its effectiveness in reducing crash ratesfor the target group via a randomised control trial. A process evaluation was also conducted toexamine program delivery in parallel with the outcome evaluation. The objective of this paper is topresent the process evaluation results. Data were sourced from the coaches, the program deliveryorganisation, and VicRide participants. Willingness to pay for VicRide was also obtained from thetarget novice motorcyclists. Overall the results suggest that VicRide was delivered as intended bythe design on most aspects. However, the trial also identified numerous barriers to achieve highcompletion rates for both the preparation activity and program attendance and VicRide as a roadsafety intervention was valued significantly less by program participants than control riders whohad not yet completed the program. Though the low completion rates may have negatively impactedthe program outcomes, the barriers to completion may also reflect that individualised programs suchas VicRide are practically challenging to standardise and implement as a state-wide intervention.These may be improved if all learning opportunities are contained within program attendance andthe program is made mandatory. Nevertheless, these considerations are meaningful only if andwhen VicRide and other similar programs demonstrate detectable road safety value including crashand casualty reductions, reduced risk taking behaviours and improved safety attitudes

Adjuvant radiotherapy after salvage surgery for melanoma recurrence in a node field following a previous lymph node dissection

Background and Objectives: Adjuvant radiotherapy (RT) can be given to melanoma patients following salvage surgery for node field recurrence after a previous regional node dissection, but the value of this treatment strategy is poorly documented. This study evaluated long-term node field control and survival of patients treated in this way in an era before effective adjuvant systemic therapy became available. Methods: Data for 76 patients treated between 1990 and 2011 were extracted from an institutional database. Baseline patient characteristics, treatment details and oncological outcomes were analysed. Results: Adjuvant RT with conventional fractionation (median dose 48 Gy in 20 fractions) was given to 43 patients (57%) and hypofractionated RT (median dose 33 Gy in 6 fractions) to 33 patients (43%). The 5-year node field control rate was 70%, 5-year recurrence-free survival 17%, 5-year melanoma-specific survival 26% and 5-year overall survival 25%. Conclusions: Salvage surgery with adjuvant RT achieved node field control in 70% of melanoma patients with node field recurrence following a prior node dissection. However, disease progression at distant sites was common and survival outcomes were poor. Prospective data will be required to assess outcomes for contemporary combinations of surgery, adjuvant RT and systemic therapy.</p