Structural estimation of a principal-agent model: moral hazard in medical insurance

Despite the importance of principal-agent models in the development of modern economic theory, there are few estimations of these models. I recover the estimates of a principal-agent model and obtain an approximation to the optimal contract. The results show that out-of-pocket payments follow a concave profile with respect to costs of treatment. I estimate the welfare loss due to moral hazard, taking into account income effects. I also propose a new measure of moral hazard based on the conditional correlation between contractible and noncontractible variables

Quality externalities among hotel establishments: what is the impact of tour operators?

This paper is about quality decisions in a vertical structure where competitive producers sell to powerful retailers. Specifically, we focus the analysis on the role played by a tour operator (TO) on quality investments when distributing the capacity of a given tourist destination. We emphasize the presence of quality externalities among hotel establishments, and see that sometimes a TO distribution can provide a solution to the tragedy of the commons in qualityprovision. Thus, we analyze what implications do vertical relations have for quality in this industry, and then derive some policy recommendations. This paper is about quality decisions in a vertical structure where competitive producers sell to powerful retailers. Specifically, we focus the analysis on the role played by a tour operator (TO) on quality investments when distributing the capacity of a given tourist destination. We emphasize the presence of quality externalities among hotel establishments, and see that sometimes a TO distribution can provide a solution to the tragedy of the commons in qualityprovision. Thus, we analyze what implications do vertical relations have for quality in this industry, and then derive some policy recommendations

A Fast and Accurate Universal Kepler Solver without Stumpff Series

We derive and present a fast and accurate solution of the initial value problem for Keplerian motion in universal variables that does not use the Stumpff series. We find that it performs better than methods based on the Stumpff series.Comment: 10 pages, 7 figures. Accepted by MNRAS, resubmitted because of a typo in the title, added author affiliation

Early evaluation of a new nutrition and education programme in Colombia

From introduction: In recent years, international financial institutions, policy-makers and economists have paid considerable attention to micro development policies based on cash transfers targeted to poor families and released only if the potential beneficiaries comply with specific conditions. Such conditional cash transfers have been particularly popular in education and nutrition policies – that is, in policies whose aim is to foster the accumulation of human capital among young children. In the case of the nutrition interventions, the conditions are often that the mother of the children, who receives the transfers, enrols them to development and growth check-ups and/or attends hygiene, vaccination and contraception courses. Much of the attention on conditional transfer programmes originated from the perceived success of a large programme of this nature started in rural Mexico in 1998 and evaluated scientifically with semi-experimental methods. Since the evidence on PROGRESA, as the Mexican programme was known, has received much attention, several international organisations have been promoting similar interventions in many developing countries and in particular in Latin America. It should be stressed that while PROGRESA has been widely branded as a success and has surely improved the nutritional and development outcomes of very young children and enrolment for secondary school, the reasons behind this success are not entirely obvious. In particular, it is not completely clear whether the conditionalities imposed by the programme played a role in determining the outcomes and what that role was

Dissipating the Langevin equation in the presence of an external stochastic potential

In the Langevin formalism, the delicate balance maintained between the fluctuations in the system and their corresponding dissipation may be upset by the presence of a secondary, space-dependent stochastic force, particularly in the low friction regime. In prior work, the latter was dissipated self-consistently through an additional uniform (mean-field) friction [Shepherd and Hernandez, J. Chem. Phys., 115, 2430-2438 (2001).] An alternative approach to ensure that equipartition is satisfied relies on the use of a space-dependent friction while ignoring nonlocal correlations. The approach is evaluated with respect to its ability to maintain constant temperature for two simple one-dimensional, stochastic potentials of mean force wherein the friction can be evaluated explicitly when there is no memory in the barriers. The use of a space-dependent friction is capable of providing qualitatively similar results to those obtained previously, but in extreme cases, deviations from equipartition may be observed due to the neglect of the memory effects present in the stochastic potentials.Comment: 9 pages, 5 figures, to appear in J. Chem. Phy

Copyright Protection of Color Imaging Using Robust-Encoded Watermarking

In this paper we present a robust-encoded watermarking method applied to color images for copyright protection, which presents robustness against several geometric and signal processing distortions. Trade-off between payload, robustness and imperceptibility is a very important aspect which has to be considered when a watermark algorithm is designed. In our proposed scheme, previously to be embedded into the image, the watermark signal is encoded using a convolutional encoder, which can perform forward error correction achieving better robustness performance. Then, the embedding process is carried out through the discrete cosine transform domain (DCT) of an image using the image normalization technique to accomplish robustness against geometric and signal processing distortions. The embedded watermark coded bits are extracted and decoded using the Viterbi algorithm. In order to determine the presence or absence of the watermark into the image we compute the bit error rate (BER) between the recovered and the original watermark data sequence. The quality of the watermarked image is measured using the well-known indices: Peak Signal to Noise Ratio (PSNR), Visual Information Fidelity (VIF) and Structural Similarity Index (SSIM). The color difference between the watermarked and original images is obtained by using the Normalized Color Difference (NCD) measure. The experimental results show that the proposed method provides good performance in terms of imperceptibility and robustness. The comparison among the proposed and previously reported methods based on different techniques is also provided