Essays on the use of probabilistic machine learning for estimating customer preferences with limited information

In this thesis, I explore in two essays how to augment thin historical purchase data with other sources of information using Bayesian and probabilistic machine learning frameworks to better infer customers' preferences and their future behavior. In the first essay, I posit that firms can better manage recently-acquired customers by using the information from acquisition to inform future demand preferences for those customers. I develop a probabilistic machine learning model based on Deep Exponential Families to relate multiple acquisition characteristics with individual level demand parameters, and I show that the model is able to capture flexibly non-linear relationships between acquisition behaviors and demand parameters. I estimate the model using data from a retail context and show that firms can better identify which new customers are the most valuable. In the second essay, I explore how to combine the information collected through the customer journey—search queries, clicks and purchases; both within-journeys and across journeys—to infer the customer’s preferences and likelihood of buying, in settings in which there is thin purchase history and where preferences might change from one purchase journey to another. I propose a non-parametric Bayesian model that combines these different sources of information and accounts for what I call context heterogeneity, which are journey-specific preferences that depend on the context of the specific journey. I apply the model in the context of airline ticket purchases using data from one of the largest travel search websites and show that the model is able to accurately infer preferences and predict choice in an environment characterized by very thin historical data. I find strong context heterogeneity across journeys, reinforcing the idea that treating all journeys as stemming from the same set of preferences may lead to erroneous inferences

Lifestyle intervention as a treatment for obesity in school-age-children in Celaya, Guanajuato: An experimental study

Introduction: Obesity is a risk factor in chronic diseases, and its frequency among children in Mexico is increasing. Objective: To determine the effect of lifestyle intervention as a treatment for obesity in school-age-children from Celaya, Mexico.Methodology: For this experimental study, four schools were randomly selected. Children and parents participated voluntarily and signed consent forms. Two schools were chosen as the experimental group and the other two formed the control group. Age, gender, weight, height, BMI and blood pressure were recorded for each participant. Intervention: Children and parents were asked to walk in their schools for 30 minutes a day Monday through Friday and to attend 8 instructional sessions over a period of four months dedicated to the selection and preparation of meals. Statistical Analysis: The OR and 95% CI were calculated to determine the effect of the intervention; a Z-test for two proportions for overweight and obesity in the control and experimental groups were carried out for comparison.Results: 157 children were included in the experimental group and 144 in the control group. To compare the proportions of the overweight and the obese between the groups, a Z-test = - 0.36 (p-value 0.72) were obtained showing no effect of the intervention in lifestyle; OR =1.09, 95% CI (0.67, 1.77). It was adjusted according to the attendance to the sessions resulting in an OR = 2.00, 95% CI (0.69, 5.77), demonstrating that not attending the sessions was a confounder.Conclusions: Intervention in lifestyle should be measured over a longer period of time in order to determine what effects it may have on changes in body mass index

Is the Supercourse useful for Latin America?

BACKGROUND: The success of the Supercourse showed that the effort was needed in Latin America. But would a Spanish language version be better for the region? METHODS: Google Analytics was used to determine website usage. A custom evaluation form was created to get user feedback on the usefulness of both the English language and Spanish language Supercouse lectures. RESULTS: Over a year's span from June 2009 to June 2010 there were 257,403 unique visits and 448,939 page views. The overall average rating of lectures was 4.87 with the Spanish language lectures getting even higher ratings. CONCLUSION: Supercourse lectures in Spanish were a great success in Latin America. This success shows the need for this information and similar success could be found in Central Asia

Is the Supercourse useful for Latin America?

BACKGROUND: The success of the Supercourse showed that the effort was needed in Latin America. But would a Spanish language version be better for the region?METHODS: Google Analytics was used to determine website usage. A custom evaluation form was created to get user feedback on the usefulness of both the English language and Spanish language Supercouse lectures.RESULTS: Over a year's span from June 2009 to June 2010 there were 257,403 unique visits and 448,939 page views. The overall average rating of lectures was 4.87 with the Spanish language lectures getting even higher ratings.CONCLUSION: Supercourse lectures in Spanish were a great success in Latin America. This success shows the need for this information and similar success could be found in Central Asia

Perfect Intrinsic Squeezing at the Superradiant Phase Transition Critical Point

Some of the most exotic properties of the quantum vacuum are predicted in ultrastrongly coupled photon–atom systems; one such property is quantum squeezing leading to suppressed quantum fluctuations of photons and atoms. This squeezing is unique because (1) it is realized in the ground state of the system and does not require external driving, and (2) the squeezing can be perfect in the sense that quantum fluctuations of certain observables are completely suppressed. Specifically, we investigate the ground state of the Dicke model, which describes atoms collectively coupled to a single photonic mode, and we found that the photon–atom fluctuation vanishes at the onset of the superradiant phase transition in the thermodynamic limit of an infinite number of atoms. Moreover, when a finite number of atoms is considered, the variance of the fluctuation around the critical point asymptotically converges to zero, as the number of atoms is increased. In contrast to the squeezed states of flying photons obtained using standard generation protocols with external driving, the squeezing obtained in the ground state of the ultrastrongly coupled photon–atom systems is resilient against unpredictable noise

Addressing the Social Aspects of a Circular Economy: A Systematic Literature Review

ABSTRACT: Circular Economy (CE) is a growing topic among scholars, industries, and governments, and is aimed at decoupling economic growth and development from the consumption of finite resources. CE incorporates different meanings, from reduce, reuse, and recycle activities, to environmental degradation or resource scarcity, and is supported by specific indicators to attain sustainable development. However, so far, there has been no agreement to measure how effective an industry/product is in making the transition from linear to circular approaches, particularly those that affect society. This research work aims to perform a systematic literature review (n = 60) to analyze and discuss how social aspects have been considered and integrated in CE research so far. Moreover, this review provides an overview of the literature on social impact within the CE, which results in three main outputs: a knowledge map of the CE, an analysis of social aspects within CE, and the theories/frameworks used to evaluate social impact of CE. Finally, this study brings to light how CE implementation can affect society and highlights the importance of social dimension in the domains of CE and a policy-making community, which could help move CE towards a sustainable development

Propuesta del diseño del manual de SMS (Safety Management System) para el area de operaciones y mantenimiento en el Grupo Río Sur S.A.

Este documento pretende gestionar el concepto de Seguridad operacional que es el estado en que el riesgo de lesiones a las personas o daños a los bienes se reduce y se mantiene en un nivel aceptable, o por debajo del mismo, por medio de un proceso continuo de identificación de peligros y gestión de riesgos. Para ello se realiza el plan de implementación del Sistema de Gestión de Seguridad Operacional con el fin de aplicarlo a la empresa Grupo Rio Sur S.A., así mismo darlo a conocer a cada uno de los empleados con su respectiva reglamentación. Grupo Rio Sur S.A. es una empresa en virtud de crecimiento y pretende fortalecer su seguridad para evitar riesgos y condiciones que pongan en peligro vidas humanas, la operación y cualquier incidencia que pueda causar un accidente. Para ello pretende identificar y establecer el nivel aceptable de seguridad operacional, promover y fortalecer la cultura de la seguridad operacional, identificar los peligros y evaluar los riesgos de manera eficaz, Implementar el S.M.S., de manera puntual, consiente y efectiva integrada a todas las operaciones de la empresa, medir de forma continua el desempeño de la Seguridad Operacional, gestionar los riesgos en el proceso del taller de mantenimiento clase I y II (limitado) al siguiente tipo de aeronav

Is the Supercourse useful for Latin America?

Abstract BACKGROUND: The success of the Supercourse showed that the effort was needed in Latin America. But would a Spanish language version be better for the region