A Simple Multiple Variance-Ratio Test Based on Ranks

Using Chow and Denning's arguments applied to the individual hypothesis test methodology of Wright (2000) I propose a multiple variance-ratio test based on ranks to investigate the hypothesis of no serial coorelation. This rank joint test can be exact if data are i.i.d.. Some Monte Carlo simulations show that its size distortions are small for observations obeying the martingale hypothesis while not being and i.i.d. process. Also, regarding size and power, it compares favorably with other popular tests.Random walk hypothesis ; non parametric test ; variance-ratio test

Threshold Effects of the Public Capital Productivity : An International Panel Smooth Transition Approach

Using a non linear panel data model we examine the threshold effects in the productivity of the public capital stocks for a panel of 21 OECD countries observed over 1965-2001. Using the so-called "augmented production function" approach, we estimate various specifications of a Panel Smooth Threshold Regression (PSTR) model recently developed by Gonzalez, Teräsvirta and Van Dijk (2004). One of our main results is the existence of strong threshold effects in the relationship between output and private and public inputs : whatever the transition mechanism specified, tests strongly reject the linearity assumption. Moreover this model allows cross-country heterogeneity and time instability of the productivity without specification of an ex-ante classification over individuals. Consequently it is posible to give estimates of productivity coefficients for both private and public capital stocks at any time and for each countries in the sample. Finally we proposed estimates of individual time varying elasticities that are much more reasonable than those previously published.Public Capital ; Panel Smooth ; Threshold Regression Models

Network Effects and Infrastructure Productivity in Developing Countries

This paper proposes to investigate the threshold effects of the productivity of infrastructure investment in developing countries within a panel data framework. Various speci.cations of an augmented production function that allow for endogenous thresholds are considered. The overwhelming outcome is the presence of strong threshold effects in the relationship between output and private and public inputs. Whatever the transition mechanism used, the testing procedures lead to strong rejection of the linearity of this relationship. In particular, the productivity of infrastructure investment generally exhibits some network effects. When the available stock of infrastructure is very low, investment in this sector has the same productivity as non-infrastructure investment. On the contrary, when a minimumnetwork is available, the marginal productivity of infrastructure investment is generally largely greater than the productivity of other investments. Finally, when the main network is achieved, its marginal productivity becomes similar to the productivity of other investment.financial economics and financial management ;

Backtesting Value-at-Risk: A GMM Duration-Based Test

This paper proposes a new duration-based backtesting procedure for VaR forecasts. The GMM test framework proposed by Bontemps (2006) to test for the distributional assumption (i.e. the geometric distribution) is applied to the case of the VaR forecasts validity. Using simple J-statistic based on the moments defined by the orthonormal polynomials associated with the geometric distribution, this new approach tackles most of the drawbacks usually associated to duration based backtesting procedures. First, its implementation is extremely easy. Second, it allows for a separate test for unconditional coverage, independence and conditional coverage hypothesis (Christoffersen, 1998). Third, feasibility of the tests is improved. Fourth, Monte-Carlo simulations show that for realistic sample sizes, our GMM test outperforms traditional duration based test. An empirical application for Nasdaq returns confirms that using GMM test leads to major consequences for the ex-post evaluation of the risk by regulation authorities. Without any doubt, this paper provides a strong support for the empirical application of duration-based tests for VaR forecasts.Value-at-Risk; backtesting; GMM; duration-based test

Modèles Non Linéaires et Prévisions

Ce rapport propose une synthèse de la littérature sur l'apport des modèles non linéaires en matière de prévision des variables économiques et financières. Il comporte trois parties. La première passe en revue les principales modélisations économétriques non linéaires. La seconde partie est consacrée à la construction des prévisions ponctuelles, des prévisions par intervalle de confiance et des densités de prévisions issues des modèles non linéaires. La troisième partie décrit les principales méthodes de validation de ces différentes formes de prévisions.Prévisions, Modèles non linéaires

Investissement scolaires et rendement des investissements post-scolaires

Document de Recherche Centre de Recherche sur l'Emploi et la Productio

Marché des changes et politique monétaire américaine : les résultats d'une étude statistique sur la période récente (26/9/78-3/12/80)

Document de Recherche Institut Orléanais de Financ

L'intégration des marchés de capitaux sous différents régimes de change

Document de Recherche Institut Orléanais de Financ