Stochastic differential equations driven by fractional Brownian motion and Poisson point process

In this paper, we study a class of stochastic differential equations with additive noise that contains a fractional Brownian motion (fBM) and a Poisson point process of class (QL). The differential equation of this kind is motivated by the reserve processes in a general insurance model, in which the long term dependence between the claim payment and the past history of liability becomes the main focus. We establish some new fractional calculus on the fractional Wiener-Poisson space, from which we define the weak solution of the SDE and prove its existence and uniqueness. Using an extended form of Krylov-type estimate for the combined noise of fBM and compound Poisson, we prove the existence of the strong solution, along the lines of Gy\"{o}ngy and Pardoux (Probab. Theory Related Fields 94 (1993) 413-425). Our result in particular extends the one by Mishura and Nualart (Statist. Probab. Lett. 70 (2004) 253-261).Comment: Published at http://dx.doi.org/10.3150/13-BEJ568 in the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

A note on a Mar\v{c}enko-Pastur type theorem for time series

In this note we develop an extension of the Mar\v{c}enko-Pastur theorem to time series model with temporal correlations. The limiting spectral distribution (LSD) of the sample covariance matrix is characterised by an explicit equation for its Stieltjes transform depending on the spectral density of the time series. A numerical algorithm is then given to compute the density functions of these LSD's

Quality of Bureaucracy and Open-Economy Macro Policies

Bureaucratic quality in terms of the level of corruption varies widely across countries, and is in general slow to evolve relative to the speed with which many economic polices can be implemented such as the imposition of capital controls. In this paper, we study the possibility that quality of bureaucracy may be an important structural determinant of open-economy macro-policies, in particular, the imposition/removal of capital controls, and financial repression. We first derive a model that delivers such a result. Bureaucratic corruption translates into reduced ability by the government to collect tax revenue. Even if capital control/financial repression is otherwise inefficient, as long as the government needs the revenue for public goods provision, it would have to rely more on capital control/financial repression. For all countries for which we can obtain relevant data, we find that more corrupt countries are indeed more likely to impose capital controls, a pattern consistent with the model's prediction. The result of this paper suggests that a premature removal of capital controls mandated by outside institutions could reduce rather than enhance economic efficiency.

The quality of bureaucracy and capital account policies

The extent of bureaucracy varies extensively across countries, but the quality of bureaucracy within a country changes more slowly than economic policies. The authors propose that the quality of bureaucracy may be an important structural determinant of open economy macroeconomic policies - especially the imposition or removal of capital control. In their model, capital controls are an instrument of financial repression. They entail efficiency loss for the economy but also generate implicit revenue for the government. The results show that bureaucratic corruption translates into the government's reduced ability to collect tax revenues. Even if capital controls and financial repression are otherwise inefficient, the government still has to rely on them to raise revenues to provide public goods. Among the countries for which the authors could get relevant data, they find that the more corrupt ones are indeed more likely to impose capital controls, a pattern consistent with the model's prediction. To deal with possible reverse causality, they use the extent of corruption in a country's judicial system, and the degree of democracy, as the instrumental variables for bureaucratic corruption. The instrumental variable regressions show the same result: more corrupt countries are associated with more severe capital controls. The results suggest that as countries develop and improve their public institutions, reducing bureaucratic corruption over time, they will choose to gradually liberalize their capital accounts. Removing capital controls prematurely when forced by outside institutions to do so could reduce rather than improve their economic efficiency.Banks&Banking Reform,Governance Indicators,Environmental Economics&Policies,Economic Theory&Research,National Governance