Single period Markowitz portfolio selection, performance gauging and duality: a variation on Luenberger's shortage function

Markowitz portfolio theory (1952) has induced research into the efficiency of portfolio management. This paper studies existing nonparametric efficiency measurement approaches for single period portfolio selection from a theoretical perspective and generalises currently used efficiency measures into the full mean-variance space. Therefore, we introduce the efficiency improvement possibility function (a variation on the shortage function), study its axiomatic properties in the context of Markowitz efficient frontier, and establish a link to the indirect mean-variance utility function. This framework allows distinguishing between portfolio efficiency and allocative efficiency. Furthermore, it permits retrieving information about the revealed risk aversion of investors. The efficiency improvement possibility function thus provides a more general framework for gauging the efficiency of portfolio management using nonparametric frontier envelopment methods based on quadratic optimisation.

An illustrated flora of the northern United States, Canada and the British possessions, from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian, by Nathaniel Lord Britton and Addison Brown. The descriptive text chiefly prepared by Britton, with the assistance of specialists in several groups; the figures also drawn under his supervision.

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An illustrated flora of the northern United States, Canada and the British possessions, from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian, by Nathaniel Lord Britton and Addison Brown. The descriptive text chiefly prepared by Britton, with the assistance of specialists in several groups; the figures also drawn under his supervision.

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User-friendly parallel computations with econometric examples

This paper shows how a high level matrix programming language may be used to perform Monte Carlo simulation, bootstrapping, estimation by maximum likelihood and GMM, and kernel regression in parallel on symmetric multiprocessor computers or clusters of workstations. The implementation of parallelization is done in a way such that an investigator may use the programs without any knowledge of parallel programming. A bootable CD that allows rapid creation of a cluster for parallel computing is introduced. Examples show that parallelization can lead to important reductions in computational time. Detailed discussion of how the Monte Carlo problem was parallelized is included as an example for learning to write parallel programs for Octave.

Parametric and semiparametric estimation of sample selection models: an empirical application to the female labour force in Portugal

This comment corrects the errors in the estimation process that appear in Martins (2001). The first error is in the parametric probit estimation, as the previously presented results do not maximize the log-likelihood function. In the global maximum more variables become significant. As for the semiparametric estimation method, the kernel function used in Martins (2001) can take on both positive and negative values, which implies that the participation probability estimates may be outside the interval [0,1]. We have solved the problem by applying local smoothing in the kernel estimation, as suggested by Klein and Spady (1993).

ParallelKnoppix - Rapid deployment of a linux cluster for MPI parallel processing using non-dedicated computers

This note describes ParallelKnoppix, a bootable CD that allows creation of a Linux cluster in very little time. An experienced user can create a cluster ready to execute MPI programs in less than 10 minutes. The computers used may be heterogeneous machines, of the IA-32 architecture. When the cluster is shut down, all machines except one are in their original state, and the last can be returned to its original state by deleting a directory. The system thus provides a means of using non-dedicated computers to create a cluster. An example session is documented.

I want you! An experiment studying the selection effect when assigning distributive power.

We study whether selection affects motivation. In our experiment subjects first answer a personality questionnaire. They then play a 3-person game. One of the three players decides between an outside option assigning him a positive amount, but leaving the two others empty-handed and allowing one of the other two players to distribute a pie. Treatments differ in the procedure by which distributive power is assigned: to a randomly determined or to a knowingly selected partner. Before making her decision the selecting player could consult the personality questionnaire of the other two players. Results show that knowingly selected players keep less for themselves than randomly selected ones and reward the selecting player more generously.

Self-selection consistent functions

This paper studies collective choice rules whose outcomes consist of a collection of simultaneous decisions, each one of which is the only concern of some group of individuals in society. The need for such rules arises in different contexts, including the establishment of jurisdictions, the location of multiple public facilities, or the election of representative committees. We define a notion of allocation consistency requiring that each partial aspect of the global decision taken by society as a whole should be ratified by the group of agents who are directly concerned with this particular aspect. We investigate the possibility of designing envy-free allocation consistent rules, we also explore whether such rules may also respect the Condorcet criterion.

The Adolpho Lutz collection of Tabanidae: (Diptera): I. The described genera and species, condition of the collection, and selection of lectotypes

A study of the Adolpho Lutz Collection of Tabanidae at the Instituto Oswaldo Cruz and of additional Lutz material at the Instituto Butantan in São Paulo is reported. Of the ninety-four species of Tabanidae validly described by Lutz, type material of eighty-four was recognized, either holotypes, allotypes or syntypes. Lectotypes were selected from among syntype series or remaining specimens and all type material was labelled. Of the ten species of which no type material could be found, neotypes were designated in the case of two species, Erephosis nigricans and Erephosis pseudo-aurimaculata. Types of three species, Chrysops ecuadoriensis, Dichelacera salvadorensis and Esenbeckia nigricorpus are believed to have been in Hamburg and destroyed during the last war. Types of two species, Esenbeckia biscutellata and E. dubia, and additional type material of several others are believed to have been in Montevideo. A request for information about them remains unanswered. Types of the remaining three species, Dichelacera intermedia, Dichelacera laceriascia and Esenbeckia distinguenda could not be found, and it is believed that at least the type of the last species was accidentally destroyed. Three specific of subspecific names proposed by Lutz but palaced by others in synonymy have been revalidated, Acanthocera intermedia, Erephosis brevistria and Esenbeckia fenestrata. Generic placement of two names has been changed, Esenbeckia arcuata ricardoae to Proboscoides, and Selasoma giganteum to Stibasoma. Seven specific names proposed by Lutz appear to be synonyms of earlier names, as follows: Bombylopsis juxtaleonina Lutz and Castro, 1936 = B. leonina Lutz, 1909. Bombylopsis pseudoanalis Lutz, 1909 = B. erythronotata (Bigot, 1892). Esenbeckia fuscipennis var. flavescens Lutz, 1909 = Esenbeckia fuscipennis Wied., 1828. Fidena chrysopyga Lutz and Castro, 1936 = F. atra Lutz and Castro, 1936. Laphriomyia longipalpis Lutz and Castro, 1937 = L. mirabilis Lutz, 1911. Stibasoma semiflavum Lutz, 1915 = St. bicolor Bigot, 1892. Tabanus hesperus Lutz, 1912 = Chlorotabanus (Cryptolylus) innotescens (Walker, 1854). Four Lutz names appear to antedate names proposed by others, viz.: Diachlorus angustifrons Kröber, 1930 and D. ochraceus Kröb., 1928 not Macquart, 1850 = Diachlorus fuscistigma Lutz, 1913. Psalidia fairchildi Barretto, 1950 = dicladocera conspicua Lutz and Neiva, 1914. Fidena pseudo-fulvithorax Kröb., 1931 = Erephopsis flavicrinis Lutz, 1909. Esenbeckia lemniscata Enderlein, 1925 = Esenbeckia clari Lutz, 1909. Some comments on Lutz' system of classification are given together with notes on the genotypes and included species of his genera as revaled by his collection and notes.

Entry and market selection of firms: a laboratory study

We study competition in experimental markets in which two incumbents face entry by three other firms. Our treatments vary with respect to three factors: sequential vs. block or simultaneous entry, the cost functions of entrants and the amount of time during which incumbents are protected from entry. Before entry incumbents are able to collude in all cases. When all firms' costs are the same entry always leads consumer surplus and profits to their equilibrium levels. When entrants are more efficient than incumbents, entry leads consumer surplus to equilibrium. However, total profits remain below equilibrium, due to the fact that the inefficient incumbents produce too much and efficient entrants produce too little. Market behavior is satisfactory from the consumers' standpoint, but does not yield adequate signals to other potential entrants. These results are not affected by whether entry is simultaneous or sequential. The length of the incumbency phase does have some subtle effects.

Trypanosoma cruzi: strain selection by diferent schedules of mouse passage of an initially mixed infection

From an initial double infection in mice, established by simultaneous and equivalent inocula of bloodstream forms of strains Y and F of Trypanosoma cruzi, two lines were derived by subinoculations: one (W) passaged every week, the other (M) every month. Through biological and biochemical methods only the Y strain was identified at the end of the 10th and 16th passages of line W and only the F strain at the 2nd and 4th passages of line M. The results illustrate strain selection through laboratory manipulation of initially mixed populations of T. cruzi.

Orientation of the snail Biomphalaria straminea (Dunker, 1848) in response to light in a situation of selection

The behavioral response of Biomphalaria straminea to light was evaluted in terms of location of the snail in a Y-shaped aquarium in a situation of selection and of the rate (cm/hour) and direction of locomotion under homogeneous 9vertical) or differential (horizontal) lighting upon only one arm of the aquarium. The light source consisted of daylight fluorescent lamps with a spectrum close to that of natural light, with illumination varying from 28 to 350 lux. Analysis of the data showed that all animals, whether in groups or isolated, were attracted to light, although the time needed to approach the light source was 50% shorter for the former than for the latter. The rate of locomotion of B. straminea was 35% higher than observed in B. glabrata and 51% higher than that observed in B. tenagophila studied under similar conditions. The results are discussed in terms of social factors and geographical distribution of the three species.

Wealth constraints, skill prices or networks: what determines emigrant selection?

The productive characteristics of migrating individuals, emigrant selection, affect welfare. The empirical estimation of the degree of selection suffers from a lack of complete and nationally representative data. This paper uses a new and better dataset to address both issues: the ENET (Mexican Labor Survey), which identifies emigrants right before they leave and allows a direct comparison to non-migrants. This dataset presents a relevant dichotomy: it shows on average negative selection for Mexican emigrants to the United States for the period 2000-2004 together with positive selection in Mexican emigration out of rural Mexico to the United States in the same period. Three theories that could explain this dichotomy are tested. Whereas higher skill prices in Mexico than in the US are enough to explain negative selection in urban Mexico, its combination with network effects and wealth constraints is required to account for positive selection in rural Mexico.