Composite Fading Models based on Inverse Gamma Shadowing: Theory and Validation

We introduce a general approach to characterize composite fading models based on inverse gamma (IG) shadowing. We first determine to what extent the IG distribution is an adequate choice for modeling shadow fading, by means of a comprehensive test with field measurements and other distributions conventionally used for this purpose. Then, we prove that the probability density function and cumulative distribution function of any IG-based composite fading model are directly expressed in terms of a Laplace-domain statistic of the underlying fast fading model and, in some relevant cases, as a mixture of wellknown state-of-the-art distributions. Also, exact and asymptotic expressions for the outage probability are provided, which are valid for any choice of baseline fading distribution. Finally, we exemplify our approach by presenting several application examples for IG-based composite fading models, for which their statistical characterization is directly obtained in a simple form.Comment: This work has been submitted to the IEEE for publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

On the Utility of the Inverse Gamma Distribution in Modeling Composite Fading Channels

We introduce a general approach to characterize composite fading models based on inverse gamma (IG) shadowing. We first determine to what extent the IG distribution is an adequate choice for modeling shadow fading, by means of a comprehensive test with field measurements and other distributions conventionally used for this purpose. Then, we prove that the probability density function and cumulative density function of any IG-based composite fading model are directly expressed in terms of a Laplace-domain statistic of the underlying fast fading model, and in some relevant cases, as a mixture of well-known state-of-the-art distributions. We exemplify our approach by presenting a composite IG/two-wave with diffuse power fading model, for which its statistical characterization is directly attained in a simple form.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The accounting dimension in financial integration: International pricing under different accounting standards

We suggest that accounting homogeneity is a necessary step in the process of financial market integration. Specifically, we analyze the effect of integration in the “accounting sense” in the correct analysis of international investments and fund allocation by estimating several pricing and valuation models in a cross-country context. We design our analysis in such a way that we can control for differences in accounting standards of the firms contained in the sample. Our results show that the accounting dimension is relevant for cross-country pricing and valuation: the use of homogeneous accounting leads to higher goodness-of-fit of international versions of the models, at levels similar to those of domestic versions and superior to those of non-homogeneous versions. Our results imply that accounting integration is an additional, and important, dimension of financial integration and that progress towards further accounting homogeneity would lead to more accurate pricing of international assets and to an improvement of the efficiency of international fund allocation.

On the strategic equivalence of multiple-choice test scoring rules

A disadvantage of multiple-choice tests is that students have incentives to guess. To discourage guessing, it is common to use scoring rules that either penalize wrong answers or reward omissions. These scoring rules are considered equivalent in psychometrics, although experimental evidence has not always been consistent with this claim. We model students' decisions and show, first, that equivalence holds only under risk neutrality and, second, that the two rules can be modified so that they become equivalent even under risk aversion. This paper presents the results of a field experiment in which we analyze the decisions of subjects taking multiple-choice exams. The evidence suggests that differences between scoring rules are due to risk aversion as theory predicts. We also find that the number of omitted items depends on the scoring rule, knowledge, gender and other covariates.risk aversion, scoring rules, field experiment, multiple choice tests

Optimal Correction for Guessing in Multiple-Choice Tests

Building on Item Response Theory we introduce students’ optimal behavior in multiple-choice tests. Our simulations indicate that the optimal penalty is relatively high, because although correction for guessing discriminates against risk-averse subjects, this effect is small compared with the measurement error that the penalty prevents. This result obtains when knowledge is binary or partial, under different normalizations of the score, when risk aversion is related to knowledge and when there is a pass-fail break point. We also find that the mean degree of difficulty should be close to the mean level of knowledge and that the variance of difficulty should be high.Item Response Theory, formula scoring, multiple choice tests

Can cognitive performance predict physical fitness and academic achievement one year later?

Previous studies have shown that physical activity, fitness and academic achievement might predict cognitive performance later in life . However, to the best of our knowledge, there are no studies examining the inverse relationship, that is, whether cognition may predict fitness and academic achievement in adolescents one year later . Therefore, the aim of this study was to examine the associations between cognitive performance and physical fitness and academic achievement one year later .Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Performance evaluation of space-time block coding using a realistic mobile radio channel

This paper presents a performance evaluation of space-time block coding (STBC) employing a realistic mobile radio channel model in macrocellular and urban environments. The bit error rate (BER) is computed by Monte-Carlo simulations in the down-link to evaluate its sensitivity to channel correlation. We consider a horizontal uniform linear array at the base station (BS) formed by up to four antenna elements, and one and two uncorrelated antenna elements at the mobile station (MS). The channel model includes the probability density function (pdf) of the azimuth and delay of the impinging waves and their expected power conditioned on the azimuth and delay. The statistical properties of the model are extracted from macrocellular measurements made in urban environments. Simulation results show that the use of STBC can provide significant gains with acceptable sensitivity to the channel correlation under realistic conditions.Peer ReviewedPostprint (published version

Proyectos de Paz del Siglo de la Ilustración (III. William Penn: el iniciador)

Plan Nacional de I+D+I PAIDESOC FFI2017-82272-