Showing papers by "Instituto Tecnológico Autónomo de México published in 1993"
TL;DR: Two methods are proposed for selecting a variance-stabilizing transformation and another for bias-reduction of the forecast in the original scale, which can be employed with practically any type of time-series model.
Abstract: This paper presents some procedures aimed at helping an applied time-series analyst in the use of power transformations. Two methods are proposed for selecting a variance-stabilizing transformation and another for bias-reduction of the forecast in the original scale. Since these methods are essentially model-independent, they can be employed with practically any type of time-series model. Some comparisons are made with other methods currently available and it is shown that those proposed here are either easier to apply or are more general, with a performance similar to or better than other competing procedures.
120 citations
TL;DR: In this paper, a Bayesian approach is used to derive constrained and unconstrained forecasts in an autoregressive time series model, which are obtained by formulating an AR( p ) model in such a way that it is possible to compute numerically the predictive distribution for any number of forecasts.
22 citations
TL;DR: Sometimes data analysis using the usual parametric techniques produces misleading results due to violations of the underlying assumptions, such as outliers or non-constant variances, in unreplicated factorial or fraction analysis.
Abstract: Sometimes data analysis using the usual parametric techniques produces misleading results due to violations of the underlying assumptions, such as outliers or non-constant variances. In particular, this could happen in unreplicated factorial or fraction..
21 citations
TL;DR: A method is presented to improve the precision of timely data, which are published when final data are not yet available, by derived explicit statistical formulae equivalent to Kalman filtering to combine historical with preliminary information.
15 citations
01 Jan 1993
TL;DR: A neural net model of the reti-no-tectal-pretectal interactions is used to analyze how its activation dynamics may underly prey-catching behavior, and it is postulated that toad’s motivational state might modulate the intensity and temporal characteristics of pretectal activation.
Abstract: In this paper, we follow an hibrid approach —a theory- experiment cycle— for the study of visuomotor coordination in amphibians (e.g., toads). We use a neural net model of the reti-no-tectal-pretectal interactions to analyze, via computer simulations and mathematical analyses, how its activation dynamics may underly prey-catching behavior. In particular, we study how changes in the hypothesized pretectal inhibitory effect over tectum might account for the modulation of prey-like stimuli discrimination. Our analysis shows, at the tectal level, that the efficacy of the stimulus characteristics (e.g., form and velocity) to produce the proper discrimination between different stimuli (e.g., worm-like and square) depends on the intensity and temporal characteristics of pretectal activation. Then, we explored this prediction experimentally, in toad Bufo marinus horribilis, by changing some of the motivational factors that affect toad’s response frequency to prey-like stimuli. Animals under different maintenance conditions in the laboratory (i.e., relationship between feeding and stimulation time) were stimulated with worm- like and square stimuli moving at different velocities. We found that the stimulus characteristics might become irrelevant to produce optimal prey-catching behavior. These combined, mathematical and experimental, analyses allow us to postulate that toad’s motivational state might modulate the intensity and temporal characteristics of pretectal activation.
10 citations
01 Jan 1993
TL;DR: In this article, the authors analyze some of the methodological obstacles that create conflicts among the different disciplines that form Cognitive Science and set forth specific methodological considerations that might lead towards the amelioration of the isolation problem which results from the fact that each area of Cognitive Science has been developed in almost complete independence of the others.
Abstract: This book is the result of a meeting where neuroscientists and computer scientits explored the possibility of developing common ground for the study of intelligent behavior in animals and machines. Here, we analyze some of the methodological obstacles that create conflicts among the different disciplines that form Cognitive Science. Our aim is to set forth specific methodological considerations that might lead towards the amelioration of the Isolation Problem which results from the fact that each area of Cognitive Science has been developed in almost complete independence of the others. We argue that Isolation Problem has been in great part generated by the misuse of linguistic terms associated with mental events.
2 citations
01 Jan 1993
TL;DR: In this article, the authors explore several transversality conditions in an attempt to define the budget set of a consumer in an incomplete financial market, and show that these conditions entail an infinite number of effective constraints on future savings and produce certain types of discontinuities in the budget sets not found in the complete markets model.
Abstract: Publisher Summary This chapter discusses some properties of equilibrium prices for dynamic economies with incomplete financial markets. In these economies, wealth cannot be transferred freely over time and across states of nature. Therefore, agents are subject to idiosyncratic risk, and may attach different valuations to certain assets or streams of wealth. The chapter explores several transversality conditions in an attempt to define the budget set of a consumer. These conditions entail an infinite number of effective constraints on future savings and produce certain types of discontinuities in the budget sets not found in the complete markets model. Continuity is, under mild conditions, obtained if the pattern of wealth evolves according to the probability distribution and the discount factor. The conditional probability belongs to the span of the financial structure. Another feature of these economies is that they contain equilibria of finite wealth that may coexist with others in which the wealth is infinite.
2 citations
01 Jan 1993
TL;DR: The realidad que nos muestran las investigaciones de las ultimas decadas sobre mujer and trabajo, tanto en el area rural como en la urbana, deja poco espacio para las esperanzas puestas en el desarrollo y la modernizacion como factores de cambio inmediato y positivo as mentioned in this paper.
Abstract: Las investigaciones recientes sobre la insercion de las mujeres en el mercado de trabajo ofrecen una serie de datos estadisticos que muestran -de manera cruda- la situacion claramente desventajosa de las mujeres trabajadoras en el Mexico actual. Frente a la ilusion moderna de que el descenso demografico y la salida del hogar pondran termino a la opresion femenina, la realidad que nos muestran las investigaciones de las ultimas decadas sobre mujer y trabajo, tanto en el area rural como en la urbana, deja poco espacio para las esperanzas puestas en el desarrollo y la modernizacion como factores de cambio inmediato y positivo.
2 citations
Journal Article•
1 citations