Flexible modelling of neuron firing rates across different experimental conditions: an application to neural activity in the prefrontal cortex during a discrimination task

Summary.  In many electrophysiological experiments the main objectives include estimation of the firing rate of a single neuron, as well as a comparison of its temporal evolution across different experimental conditions. To accomplish these two goals, we propose a flexible approach based on the logistic generalized additive model including condition-by-time interactions. If an interaction of this type is detected in the model, we then establish that the use of the temporal odds ratio curves is very useful in discriminating between the conditions under which the firing probability is higher. Bootstrap techniques are used for testing for interactions and constructing pointwise confidence bands for the true odds ratio curves. Finally, we apply the new methodology to assessing relationships between neural response and decision-making in movement-selective neurons in the prefrontal cortex of behaving monkeys.     

An Analysis of the Relationship between Environmental Motivations and ISO14001 Certification

The objectives of this paper are both to identify the environmental motivations associated with the decision to initiate the process for ISO14001 certification and to check whether such motivations undergo any changes once the company obtains its certification and experiences the actual effects of this process. Based on the work of Bansal and Roth, we distinguish between ethical, competitive and relational motivations, and compare the importance of these motivations in four company stages with respect to the ISO14001 certification: not considered, considered, in process and awarded. This comparison was performed through a logit analysis applied over the data supplied by 184 Spanish manufacturers from three different industrial sectors. It was concluded that the decision to pursue the ISO14001 certification responds to ethical and competitive motivations, and that once the company gets its certification, the company portfolio of environmental motivations does not change significantly.     

UNILINGUAL VERSUS BILINGUAL EDUCATION: A POLITICAL ECONOMY ANALYSIS

We consider an economy with two language groups, where only agents who share a language can produce together. Schooling enhances the productivity of students. Individuals attending a unilingual school end up speaking the language of instruction only, whereas bilingual schools render individuals bilingual atthe same cost. The politically dominant group (not necessarily the majority) chooses the type(s) of schools accessible to each language group, and then individuals decide whethertoattend school. Weshow that the dominant either choose laissez‐faireor restrict access to schools in the language of the dominated. Instead, the dominated favour the use of their own language. Thus, although agents do not derive utility from speaking their mother tongue, language conflicts of the expected type endogenously arise. Democracy (majority rule) always leads to the implementation of a socially optimal education system, whereas restrictions to the use of the language of the dominated are implemented too often under minority rule. The model is consistent with evidence from Belgium, France, and Finland. (JEL: I2, J15)     

ON THE IMPUTATION OF RENTAL PRICES TO OWNER‐OCCUPIED HOUSING

This paper challenges the usual objections to the possibility of applying the rental equivalent approach to determine the weight that nonrental housing services should have in the Consumer Price Index (CPI). Using data from two Spanish household budget surveys, it is shown that market rents can be well represented in terms of an index of housing quality, two geographical variables, and the year of occupancy. This parsimonious empirical model is used to impute a rental value to nonrental housing units, taking into account the possible selection bias induced by systematic differences in housing characteristics between the market rental sector and the nonrental stock. On average, the estimated hedonic values are relatively close to the self‐imputations provided in the household surveys by the occupants of such dwellings. Therefore, using either of the two alternatives to assess the importance of nonrental housing services in the CPI have small consequences for inflation. Instead, dropping these services from the CPI creates a downward bias in the measurement of inflation of 0.33 percentage points per year during 1985–1992, and an upward bias of 0.38 percentage points per year during 1993 to 2000. (JEL: C43, D12, R21, C21, E31)     

The hispanic writings of C. Wright Mills: A study in social psychology

The purpose of this article is to conduct a social-psychological analysis of C. Wright Mills and his “Hispanic writings.” I demonstrate how Mills's social-psychological theoretical framework, as articulated in Character and Social Structure, is attendant in his comments on Latinos and Latin America—a population and geopolitical region for which he seemed to have a compelling if somewhat distant fascination. I conclude with a synopsis and appraisal of: (1) Mills's personal perceptions of Latinos; (2) the social structural factors that impacted on the four Latino groups, and (3) the personality traits of Latinos as Mills saw them.     

On matric variate-T distribution

In this paper matric variate-t distribution has been studied. A factorization of the density is obtained in terms of the product of independent multivariate t- and F-densities. Further, the distributions of TAT1 and ATB, for given non-singular matrices A and B, are derived.     

ROC curve and covariates: extending induced methodology to the non-parametric framework

Continuous diagnostic tests are often used to discriminate between diseased and healthy populations. The receiver operating characteristic (ROC) curve is a widely used tool that provides a graphical visualisation of the effectiveness of such tests. The potential performance of the tests in terms of distinguishing diseased from healthy people may be strongly influenced by covariates, and a variety of regression methods for adjusting ROC curves has been developed. Until now, these methodologies have assumed that covariate effects have parametric forms, but in this paper we extend the induced methodology by allowing for arbitrary non-parametric effects of a continuous covariate. To this end, local polynomial kernel smoothers are used in the estimation procedure. Our method allows for covariate effect not only on the mean, but also on the variance of the diagnostic test. We also present a bootstrap-based method for testing for a significant covariate effect on the ROC curve. To illustrate the method, endocrine data were analysed with the aim of assessing the performance of anthropometry for predicting clusters of cardiovascular risk factors in an adult population in Galicia (NW Spain), duly adjusted for age. The proposed methodology has proved useful for providing age-specific thresholds for anthropometric measures in the Galician community.     

Comment on testing for spurious and cointegrated regressions: a wavelet approach

In a recent paper, Leong and Huang [6] proposed a wavelet-correlation-based approach to test for cointegration between two time series. However, correlation and cointegration are two different concepts even when wavelet analysis is used. It is known that statistics based on non-stationary integrated variables have non-standard asymptotic distributions. However, wavelet analysis offsets the integrating order of non-stationary series so that traditional asymptotics on stationary variables suffices to ascertain the statistical properties of wavelet-based statistics. Based on this, this note shows that wavelet correlations cannot be used as a test of cointegration.