Time series aggregation, disaggregation and long memory

We study the aggregation/disaggregation problem of random parameter AR(1) processes and its relation to the long memory phenomenon. We give a characterization of a subclass of aggregated processes which can be obtained from simpler, "elementary", cases. In particular cases of the mixture densities, the structure (moving average representation) of the aggregated process is investigated

Los indios vienen marchando : Experiencias en talleres infantiles de arqueología

El programa de difusión científica "De vacaciones con los dinosaurios" se inició en febrero de 1990, con la finalidad de integrar el Museo de Ciencias Naturales de La Plata con su comunidad. A través de la iniciativa de la Secretaria de Extensión Universitaria de la Facultad de Cs. Naturales y Museo se nos dió la oportunidad de crear los Talleres Infantiles de Arqueología cuyos objetivos giraron en torno de dos aspectos fundamentales: -introducir al niño en el estudio y comprensión del desarrollo cultural del pasado a través de sus restos materiales, que constituyen el patrimonio de su comunidad. -fomentar su interés y lograr su participación activa en la valorización y preservación del patrimonio arqueológico.Facultad de Ciencias Naturales y Muse

Aggregation and long memory: recent developments ∗

Abstract. It is well-known that the aggregated time series might have very different properties from those of the individual series, in particular, long memory. At the present time, aggregation has become one of the main tools for modelling of long memory processes. We review recent work on contemporaneous aggregation of random-coefficient AR(1) and related models, with particular focus on various long memory properties of the aggregated process

Methods for injury surveillance in international cricket

Background: The varying methods of cricket injury surveillance have made direct comparison of published studies in this field impossible. Methods: A consensus regarding definitions and methods to calculate injury rates in cricket was sought between researchers in this field. This was arrived at through a variety of face to face meetings, email communication, and draft reviews between researchers from six of the major cricket playing nations. Results: It is recommended that a cricket injury is defined as any injury or other medical condition that either (a) prevents a player from being fully available for selection for a major match or (b) during a major match, causes a player to be unable to bat, bowl, or keep wicket when required by either the rules or the team's captain. Recommended definitions for injury incidence (for matches, training sessions, and seasons) and injury prevalence are also provided. It is proposed that match injury incidence is calculated using a denominator based on a standard time estimated for player exposure in matches, for the purposes of simplicity. This will allow all injury surveillance systems, including those with limited resources, to make calculations according to a standard definition. Conclusion: The consensus statement presented provides a standard which, if followed, allows meaningful comparison of injury surveillance data from different countries and time periods, which will assist in the possible identification of risk factors for injury in cricket