Poisson Models with Employer-Employee Unobserved Heterogeneity: An Application to Absence Data

We propose a parametric model based on the Poisson distribution that permits to take into account both unobserved worker and workplace heterogeneity as long as both effects are nested. By assuming that workplace and worker unobserved heterogeneity components follow a gamma and a Dirichlet distribution respectively, we obtain a closed form the unconditional density function. We estimate the model to obtain the determinants of absenteeism using linked employer-employee Canadian data from the Workplace and Employee Survey (2003). Coefficient estimates are interpreted in the framework of the typical labor-leisure model. We show that omitting unobserved heterogeneity on either side of the employment relationship leads to notable biases in the estimated coefficients. In particular, the impact of wages on absences is underestimated in simpler models.Absenteeism, Linked Employer-Employee Data, Employer-Employee Unobserved Heterogeneity, Count Data Models, Dirichlet Distribution

Poisson Models with Employer-Employee Unobserved Heterogeneity: An Application to Absence Data

We propose a parametric model based on the Poisson distribution that permits to take into account both unobserved worker and workplace heterogeneity as long as both effects are nested. By assuming that workplace and worker unobserved heterogeneity components follow a gamma and a Dirichlet distribution respectively, we obtain a closed form for the unconditional density function. We estimate the model to obtain the determinants of absenteeism using linked employer-employee Canadian data from the Workplace and Employee Survey (2003). Coefficient estimates are interpreted in the framework of the typical labor-leisure model. We show that omitting unobserved heterogeneity on either side of the employement relationship leads to notable biases in the estimated coefficients. In particular, the impact of wages on absences is underestimated in simpler models.Absenteeism; Linked Employer-Employee Data; Employer- Employee Unobserved Heterogeneity; Count Data Models; Dirichlet Distribution

Acousto-optical coherence tomography with a digital holographic detection scheme

Acousto-optical coherence tomography (AOCT) consists in using random phase jumps on ultrasound and light to achieve a millimeter resolution when imaging thick scattering media. We combined this technique with heterodyne off-axis digital holography. Two-dimensional images of absorbing objects embedded in scattering phantoms are obtained with a good signal-to-noise ratio. We study the impact of the phase modulation characteristics on the amplitude of the acousto-optic signal and on the contrast and apparent size of the absorbing inclusion

Extension de l'aire de distribution de la Couleuvre à collier, Diadophis punctatus edwardsii, dans l'est du Québec

Deux Couleuvres à collier adulte (Diadophis punctatus edwardsii) ont été trouvées au parc national du Saguenay, dans l’est du Québec, en 2004 et 2005. Ces mentions se retrouvent à près 150 kilomètres au nord-nord-est de la mention la plus proche de l’espèce. L’habitat est constitué de forêt mixte près d’escarpements rocheux, dans des vallées. Il pourrait s’agir de populations isolées de celles retrouvées plus au sud.Two Ringneck Snakes (Diadophis punctatus edwardsii) was found in the Saguenay National Park, in eastern Québec, in 2004 and 2005. These records are about 150 kilometers north-north-east from the nearest previous record. The habitat is mixed forest, with rocky cliffs, in valleys. They may represent isolated populations from those found in southern Quebec

Full-sky CMB lensing reconstruction in presence of sky-cuts

We consider the reconstruction of the CMB lensing potential and its power spectrum of the full sphere in presence of sky-cuts due to point sources and Galactic contaminations. Those two effects are treated separately. Small regions contaminated by point sources are filled in using Gaussian constrained realizations. The Galactic plane is simply masked using an apodized mask before lensing reconstruction. This algorithm recovers the power spectrum of the lensing potential with no significant bias.Comment: Submitted to A&