Showing papers by "Instituto Tecnológico Autónomo de México published in 2019"

Inputs, Incentives, and Complementarities in Education: Experimental Evidence from Tanzania

Abstract: We present results from a large-scale randomized experiment across 350 schools in Tanzania that studied the impact of providing schools with (i) unconditional grants, (ii) teacher incentives based on student performance, and (iii) both of the above. After two years, we find (i) no impact on student test scores from providing school grants, (ii) some evidence of positive effects from teacher incentives, and (iii) significant positive effects from providing both programs. Most important, we find strong evidence of complementarities between the programs, with the effect of joint provision being significantly greater than the sum of the individual effects. Our results suggest that combining spending on school inputs (the default policy) with improved teacher incentives could substantially increase the cost-effectiveness of public spending on education.

New Results on Parameter Estimation via Dynamic Regressor Extension and Mixing: Continuous and Discrete-time Cases

Abstract: We present some new results on the dynamic regressor extension and mixing parameter estimators for linear regression models recently proposed in the literature. This technique has proven instrumental in the solution of several open problems in system identification and adaptive control. The new results include: (i) a unified treatment of the continuous and the discrete-time cases; (ii) the proposal of two new extended regressor matrices, one which guarantees a quantifiable transient performance improvement, and the other exponential convergence under conditions that are strictly weaker than regressor persistence of excitation; and (iii) an alternative estimator ensuring parameter estimation in finite-time that retains its alertness to track time-varying parameters. Simulations that illustrate our results are also presented.

Factorial Designs, Model Selection, and (Incorrect) Inference in Randomized Experiments

Abstract: Factorial designs are widely used for studying multiple treatments in one experiment. While “long” model t-tests provide valid inferences, “short” model t-tests (ignoring interactions) yield higher power if interactions are zero, but incorrect inferences otherwise. Of 27 factorial experiments published in top-5 journals (2007–2017), 19 use the short model. After including all interactions, over half their results lose significance. Modest local power improvements over the long model are possible, but with lower power for most values of the interaction. If interactions are not of interest, leaving the interaction cells empty yields valid inferences and global power improvements.

The Violent Consequences of Trade-Induced Worker Displacement in Mexico

Abstract: Mexican manufacturing job loss induced by competition with China increases cocaine trafficking and violence, particularly in municipalities with transnational criminal organizations. When it becomes more lucrative to traffic drugs because changes in local labor markets lower the opportunity cost of criminal employment, criminal organizations plausibly fight to gain control. The evidence supports a Becker-style model in which the elasticity between legitimate and criminal employment is particularly high where criminal organizations lower illicit job search costs, where the drug trade implies higher pecuniary returns to violent crime, and where unemployment disproportionately affects low-skilled men.

The Pipeline Repertoire for Ig-Seq Analysis.

Abstract: With the advent of high-throughput sequencing of immunoglobulin genes (Ig-Seq), the understanding of antibody repertoires and their dynamics among individuals and populations has become an exciting area of research. There is an increasing number of computational tools that aid in every step of the immune repertoire characterization. However, since not all tools function identically, every pipeline has its unique rationale and capabilities, creating a rich blend of useful features that may appear intimidating for newcomer laboratories with the desire to plunge into immune repertoire analysis to expand and improve their research; hence, all pipeline strengths and differences may not seem evident. In this review we provide a practical and organized list of the current set of computational tools, focusing on their most attractive features and differences in order to carry out the characterization of antibody repertoires so that the reader better decides a strategic approach for the experimental design, and computational pathways for the analyses of immune repertoires.

Generation of ECG signals from a reaction-diffusion model spatially discretized.

Abstract: We propose a model to generate electrocardiogram signals based on a discretized reaction-diffusion system to produce a set of three nonlinear oscillators that simulate the main pacemakers in the heart. The model reproduces electrocardiograms from healthy hearts and from patients suffering various well-known rhythm disorders. In particular, it is shown that under ventricular fibrillation, the electrocardiogram signal is chaotic and the transition from sinus rhythm to chaos is consistent with the Ruelle-Takens-Newhouse route to chaos, as experimental studies indicate. The proposed model constitutes a useful tool for research, medical education, and clinical testing purposes. An electronic device based on the model was built for these purposes

Time goes by so slowly (for those who wait): a field experiment in health care

Abstract: We exploit a unique field experiment to recover the willingness to pay (WTP) for shorter waiting times at a cataract detection clinic in Mexico City, and compare the results with those obtained through a hypothetical dichotomous choice questionnaire. The WTP to avoid a minute of wait obtained from the field experiment ranges from 0.59 to 0.82 Mexican pesos (1 USD = 12.5 Mexican pesos at the time of the survey), while that from the hypothetical choice experiment ranges from 0.33 to 0.48 Mexican pesos. WTP to avoid the wait is lower for lower income individuals, and it is larger the more accurately the announced expected waiting time matches the true values. Finally, we find evidence that the marginal disutility of waiting is not constant.

Reducing the harmful effect of work overload on creative behaviour: Buffering roles of energy‐enhancing resources

Abstract: This study investigates how employees' perceptions of work overload might reduce their creative behaviours and how this negative relationship might be buffered by employees' access to three energy‐enhancing resources: their passion for work, their ability to share emotions with colleagues, and their affective commitment to the organization. Data from a manufacturing organization reveal that work overload reduces creative behaviour, but the effect is weaker with higher levels of passion for work, emotion sharing, and organizational commitment. The buffering effects of emotion sharing and organizational commitment are particularly strong when they combine with high levels of passion for work. These findings indicate how organizations marked by adverse work conditions, due to excessive workloads, can mitigate the likelihood that employees avoid creative behaviours.

A globally exponentially stable speed observer for a class of mechanical systems: experimental and simulation comparison with high-gain and sliding mode designs

Abstract: It is shown in the paper that the problem of speed observation for mechanical systems that are partially linearisable via coordinate changes admits a very simple and robust (exponentially s...

The Effectiveness of Sin Food Taxes: Evidence from Mexico

Abstract: We measure the effect of a large nationwide tax reform on sugar added drinks and caloric-dense food introduced in Mexico in 2014. Using scanner data containing weekly purchases of 47,973 barcodes by 8,130 households and an RD design, we find that calories purchased from taxed drinks and taxed food decreased respectively by 2.7% and 3%. However, this was compensated by increases from untaxed categories, such that total calories purchased did not change. We find increases in cholesterol (12.6%), sodium (5.8%), saturated fat (3.1%), carbohydrates (2%), and proteins (3:8%). We conjecture that obesity is unlikely to be reduced by this tax.

The Relationship Between Individual Work Values and Unethical Decision-Making and Behavior at Work

Abstract: This paper explores the relationship between individual work values and unethical decision-making and actual behavior at work through two complementary studies. Specifically, we use a robust and comprehensive model of individual work values to predict unethical decision-making in a sample of working professionals and accounting students enrolled in ethics courses, and IT employees working in sales and customer service. Study 1 demonstrates that young professionals who rate power as a relatively important value (i.e., those reporting high levels of the self-enhancement value) are more likely to violate professional conduct guidelines despite receiving training regarding ethical professional principles. Study 2, which examines a group of employees from an IT firm, demonstrates that those rating power as an important value are more likely to engage in non-work-related computing (i.e., cyberloafing) even when they are aware of a monitoring software that tracks their computer usage and an explicit policy prohibiting the use of these computers for personal reasons.

Why Democracy Protests Do Not Diffuse

Abstract: One of the primary international factors proposed to explain the geographic and temporal clustering of democracy is the diffusion of democracy protests. Democracy protests are thought to diffuse ac...

The Law and Politics of Presidential Term Limit Evasion

Abstract: Since the turn of the millennium, a remarkably large number of incumbent presidents have managed to stay past the end of their constitutionally mandated terms. Russia’s Vladimir Putin, Rwanda’s Paul Kagame, and Colombia’s Alvaro Uribe represent a sizeable collection of presidents who were democratically elected but remained in power long past their original mandates. Such attempts to stay in office are not new, but in recent decades their nature has changed. In this Article, we present findings from an original and comprehensive survey of all evasion attempts since the year 2000. Tracing the constitutional strategies of 234 incumbents in 106 countries, we document the range of constitutional strategies these incumbents have pursued, along with how they succeeded or failed. This exercise has revealed a number of insights. First, evasion attempts are very common. Globally, no fewer than one-third of the incumbents who reached the end of their prescribed term pursued some strategy to remain in office. If we exclude the world’s strongest democracies, we find that about half of the leaders that reached the end of their term attempted to overstay. Second, and perhaps most illuminating, none of these attempts involved ignoring the constitution outright. Instead, incumbents universally displayed nominal respect for the constitution by using constitutional rules and procedures to circumvent term limits, with about two-thirds attempting to amend the constitution. But constitutional amendment is not the only legal strategy at the would-be overstayer’s disposal—presidents have tried many methods. Most notably, a number of incumbents have relied on their courts to interpret constitutional term limits out of the constitution. Other strategies uncovered by our study include: drafting a brand-new constitution and asserting that the new constitution effectively hits the “reset button” on term limits; finding a faithful-agent replacement leader whom the incumbent can control after he is out of office; and delaying elections by citing some form of political instability. Though evasion attempts are common, they are no sure thing, and often fail. Our survey is the first ever to document and analyze failed attempts. We discover that about one-third of incumbents who attempted to overstay were unsuccessful. Importantly, in the vast majority of these cases, they failed because the attempt encountered widespread popular resistance. By contrast, courts were mostly ineffectual in halting evasion attempts. This finding contradicts much of the existing literature on this subject, which has emphasized the potential role that courts can play in enforcing term limits, and thus in safeguarding against democratic erosion. If anything, our survey reveals that courts mostly do the opposite: validate the president’s attempt to remain past his term. For those who seek to enforce constitutional term limits, this finding implies that building broad resistance movements might be more effective than putting their faith in courts.

Model-based approach for household clustering with mixed scale variables

Abstract: The Ministry of Social Development in Mexico is in charge of creating and assigning social programmes targeting specific needs in the population for the improvement of the quality of life. To better target the social programmes, the Ministry is aimed to find clusters of households with the same needs based on demographic characteristics as well as poverty conditions of the household. Available data consists of continuous, ordinal, and nominal variables, all of which come from a non-i.i.d complex design survey sample. We propose a Bayesian nonparametric mixture model that jointly models a set of latent variables, as in an underlying variable response approach, associated to the observed mixed scale data and accommodates for the different sampling probabilities. The performance of the model is assessed via simulated data. A full analysis of socio-economic conditions in households in the Mexican State of Mexico is presented.

Three-Phase Fractional-Flow Theory of Foam-Oil Displacement in Porous Media With Multiple Steady States

Abstract: Understanding the interplay of foam and non-aqueous phases in porous media is key to improving the design of foam for enhanced oil recovery and remediation of aquifers and soils. A widely used implicit-texture foam model predicts phenomena analogous to cusp catastrophe theory: the surface describing foam apparent viscosity as a function of fractional flows folds backwards on itself. Thus there are multiple steady states fitting the same injection condition J defined by the injected fractional flows. Numerical simulations suggest the stable injection state among multiple possible states but do not explain the reason. We address the issue of multiple steady states from the perspective of wave propagation, using three-phase fractional-flow theory. The wave-curve method is applied to solve the two conservation equations for composition paths and wave speeds in 1D foam-oil flow. There is a composition path from each possible injection state J to the initial state I satisfying the conservation equations. The stable displacement is the one with wave speeds (characteristic velocities) all positive along the path from J to I. In all cases presented, two of the paths feature negative wave velocity at J; such a solution does not correspond to the physical injection conditions. A stable displacement is achieved by either the upper, strong-foam state or lower, collapsed-foam state, but never the intermediate, unstable state. Which state makes the displacement depends on the initial state of a reservoir. The dependence of the choice of the displacing state on initial state is captured by a boundary curve.

Fuzzy classifier based on clustering with pairs of ε-hyperballs and its application to support fetal state assessment

Abstract: Objective: In this study we propose a fuzzy classifier whose rule antecedents are determined based on the new approach to Clustering with Pairs of Prototypes (CPP). After demonstrating the high generalization ability of the classifier for six various benchmark datasets, a particular emphasis was placed on the application to support fetal state assessment based on the classification of cardiotocographic (CTG) signals. Methods: The CPP is a solution aimed at increasing the performance of fuzzy classifiers by introducing additional prototypes to those obtained using a given basal clustering method. The CPP improvement was achieved by applying the Fuzzy Clustering with e-Hyperballs (FCeH) as basal clustering, as well as a new ant algorithm-based method of searching for pairs of prototypes. Results: The results were compared with three reference methods: the Lagrangian SVM with the Gaussian kernel function, and the same fuzzy classifier, but using the antecedents determined with the fuzzy c-means and the fuzzy ( c + p ) -means clustering. In case of five out of six benchmark datasets as well as for the CTG signals classification problem we achieved the highest generalization ability measured with the classification accuracy (benchmark data) and the classification quality index defined as geometric mean of sensitivity and specificity (CTG signals). Conclusions: The results of the numerical experiments showed high accuracy of the CPP-based fuzzy classifier when assessing various types of data. Moreover, the two-step classification of the CTG signals based on the proposed method allows for the efficient signal evaluation aiming to support the automated fetal state assessment. Significance and main impact: The most significant feature of the proposed method is the high generalization ability being the result of the e-insensitive learning (FCeH clustering), while maintaining the possibility of interpreting the learning outcomes thanks to the linguistic representation of the knowledge in the form of fuzzy conditional (if-then) rules. Therefore, we believe that this solution will have a positive impact on other studies on intelligent systems.

How does mobility help distributed systems compute

Abstract: Brains are composed of connected neurons that compute by transmitting signals. The neurons are generally fixed in space, but the communication patterns that enable information processing change rapidly. By contrast, other biological systems, such as ant colonies, bacterial colonies, slime moulds and immune systems, process information using agents that communicate locally while moving through physical space. We refer to systems in which agents are strongly connected and immobile as solid, and to systems in which agents are not hardwired to each other and can move freely as liquid. We ask how collective computation depends on agent movement. A liquid cellular automaton (LCA) demonstrates the effect of movement and communication locality on consensus problems. A simple mathematical model predicts how these properties of the LCA affect how quickly information propagates through the system. While solid brains allow complex network structures to move information over long distances, mobility provides an alternative way for agents to transport information when long-range connectivity is expensive or infeasible. Our results show how simple mobile agents solve global information processing tasks more effectively than similar systems that are stationary. This article is part of the theme issue 'Liquid brains, solid brains: How distributed cognitive architectures process information'.

Transnational Board Interlocks as a Source of Non‐experiential Knowledge for the Firm in Foreign Markets

Abstract: Board interlocks between firms headquartered in different countries are increasing. We contribute to the understanding of this practice by investigating the transnational interlocks formed by the 100 largest British firms between 2011 and 2014. We explore the association between different attributes of a firm's internationalization process, namely performance, structural and attitudinal, and the extent of the firm's engagement in transnational interlocks. We posit that the value of transnational interlocks as a non‐experiential source of knowledge will vary according to which of these three attributes becomes more prominent as the firm internationalizes. We do not find a significant relationship between the performance and structural attributes of internationalization, as measured by the firm's percentage of foreign sales and assets, respectively, and increased engagement in transnational interlocks. We do, however, find an inverted U‐shaped relationship between the attitudinal attribute of internationalization, represented by the psychic dispersion of the firm's foreign operations, and the firm's number of transnational interlocks. This non‐linear relationship reveals both a natural boundary for the firm's capacity to engage in transnational interlocks and a reduced willingness to engage in such ties once a certain degree of attitudinal internationalization has been reached.

Revealing a Social Dimension of Internationalization: Transnational Board Interlocks as a Social-Based Proxy for the Degree of Internationalization of the Firm

Abstract: Systematic international diversification research depends on reliable measurements of the degree of internationalization (DOI) of the firm. In this paper, we argue that the inclusion of social markers of internationalization can contribute to the development of more robust conceptualizations of the DOI construct. Unlike traditional metrics of DOI, such as foreign sales over total sales or foreign assets over total assets, social-based metrics of internationalization can reveal less visible foreign resource interdependencies across the firm’s entire value chain. By combining social-based metrics of DOI with traditional measures of internationalization, we uncovered three distinct dimensions of internationalization: a real one, composed of the firm’s foreign sales and assets; an exposure one, represented by the firm’s extent and cultural dispersion of foreign subsidiaries; and a social one, represented by the extent of the firm’s top managers international experience and the number and cultural zone dispersion of the firm’s transnational board interlocks. Results from both an exploratory and confirmatory factor analysis show that these dimensions are sufficiently distinctive to warrant theoretical and empirical partitioning. These findings have implications for the way researchers select and combine DOI metrics and underscore the importance of conducting a thorough theoretical and statistical assessment of DOI conceptualizations before proceeding with empirical research.

Using Blockchain to Store Teachers' Certification in Basic Education in Mexico

Abstract: Blockchain has the potential to transform the financial services industry, institutional functions, business operations, and other areas such as education. The current paper focuses on one real-world illustration of Blockchain's potential - a pilot project that used a Blockchain (hosted by Ethereum) to store certifications for 1,518 teachers who participated in a teacher training in Mexico.