Alleviating Information Cocoons and Fatigue with Serendipity: Effect of Relevant Diversification and its Timing

With the rapid development of online media, in which personalized recommendations are provided, users are gaining increasingly narrow access to information, trapping them in so-called “information cocoons.” At the same time, the increase in homogenized content has brought boredom and fatigue, which are not conducive to the long-term interests of a platform. Grounded in the entertainment consumption context, as represented by the Tik Tok short video platform, this study focuses on the information cocoon reinforcement and browsing fatigue phenomena caused by the lack of proper diversification. Then, to mitigate these issues, this paper proposes relevant diversified content and diversification timing countermeasures to optimize the “what” and “when” technical designs. We explore the role of perceived serendipity as a key path toward user diversity acceptance and browsing duration, thus alleviating the phenomenon of information cocoons and browsing fatigue and facilitating the common development of platforms and users

Personalized Recommendation for Balancing Content Generation and Usage on Two-Sided Entertainment Platforms

Online entertainment platforms such as Youtube host a vast amount of user-generated content (UGC). The unique feature of two-sided UGC entertainment platforms is that creators’ content generation and users’ content usage can influence each other. However, traditional recommender systems often emphasize content usage but ignore content generation, leading to a misalignment between these two goals. To address the challenge, this paper proposes a prescriptive uplift framework to balance content generation and usage through personalized recommendations. Specifically, we first predict the heterogeneous treatment effects (HTEs) of recommended contents on creators’ content generation and users’ content usage, then consider these two predicted HTEs simultaneously in an optimization model to determine the recommended contents for each user. Using a large-scale real-world dataset, we demonstrate that the proposed recommendation method better balances content generation and usage and brings a 42% increase in participants’ activity compared to existing benchmark methods

User control and acceptance of recommender systems

Recommender systems (RS) have actively been implemented in many domains. Control mechanisms have been introduced to make recommendations more personal. However, those mechanisms have not been thoroughly studied in RS literature. This study aims to contribute to this stream of research and focuses on their relationship with the acceptance of RS among users. We utilize technology acceptance model and extend it with user control. By using an experimental setting, we measure the effect of control mechanisms on different aspects of RS acceptance

Digital user's decision journey

The landscape of the Internet is continually evolving. This creates huge opportunities for different industries to optimize vital channels online, resulting in various-forms of new Internet services. As a result, digital users are interacting with many digital systems and they are exhibiting dynamic behaviors. Their shopping behaviors are drastically different today than it used to be, with offline and online shopping interacting with each other. They have many channels to access online media but their consumption patterns on different channels are quite different. They do philanthropy online to help others but their heterogeneous motivations and different fundraising campaigns leads to distinct path-to-contribution. Understanding the digital user’s decision making process behind their dynamic behaviors is critical as they interact with various digital systems for the firms to improve user experience and improve their bottom line. In this thesis, I study digital users’ decision journeys and the corresponding digital technology firms’ strategies using inter-disciplinary approaches that combine econometrics, economic structural modeling and machine learning. The uncovered decision journey not only offer empirical managerial insights but also provide guideline for introducing intervention to better serve digital users

Satiation and cross promotion: Selling and swapping users in mobile games

One of the main challenges facing the mobile game industry is an alarming level of satiation, that is, a decline in user engagement and consequently in ad viewing, spending, and retention. Satiation lowers users’ CLV to an extent that renders acquisition from the likes of Facebook and Google untenable, driving game publishers to cross-promote, that is, sell and swap users among themselves. We model this cross-promotion as first, a screening mechanism, in that the fact of playing a game indicates specific preferences that might be suitable to an exchange with similar games; and second, as a resetting mechanism that enables the swapped users to reset their engagement in the new game, thus rendering the swap or sell beneficial to both buyer and seller. We show that there exists an optimal level of satiation with a game, and with this level, we show the conditions under which the game publisher cross promotes, and when it does, what the conditions are for selling rather than swapping. We extend the analysis to the case in which advertising costs and conversion rates are related; explain why they might be negatively correlated, and show that our main results still hold

Automatic aspect extraction in information retrieval diversity

In this master thesis we describe a new automatic aspect extraction algorithm by incorporating relevance information to the dynamics of the Probabilistic Latent Semantic Analysis. An utility-biased likelihood statistical framework is described to formalize the incorporation of prior relevance information to the dynamics of the algorithm intrinsically. Moreover, a general abstract algorithm is presented to incorporate any arbitrary new feature variables to the analysis. A tempering procedure is inferred for this general algorithm as an entropic regularization of the utility-biased likelihood functional and a geometric interpretation of the algorithm is described, showing the intrinsic changes in the information space of the problem produced when di erent sources of prior utility estimations are provided over the same data. The general algorithm is applied to several information retrieval, recommendation and personalization tasks. Moreover, a set of post-processing aspect lters is presented. Some characteristics of the aspect distributions such as sparsity or low entropy are identi ed to enhance the overall diversity attained by the diversi cation algorithm. Proposed lters assure that the nal aspect space has those properties, thus leading to better diversity levels. An experimental setup over TREC web track 09-12 data shows that the algorithm surpasses classic pLSA as an aspect extraction tool for the search diversi cation. Additional theoretical applications of the general procedure to information retrieval, recommendation and personalization tasks are given, leading to new relevanceaware models incorporating several variables to the latent semantic analysis. Finally the problem of optimizing the aspect space size for diversi cation is addressed. Analytical formulas for the dependency of diversity metrics on the choice of an automatically extracted aspect space are given under a simpli ed generative model for the relation between system aspects and evaluation true aspects. An experimental analysis of this dependence is performed over TREC web track data using pLSA as aspect extraction algorithm

Value perception and post-purchase behaviors of recurring customers: evidence in hedonic services with contractual and non-contractual linkage

[ES]Los modelos de formación de la utilidad tienen la capacidad de predecir el beneficio que los consumidores perciben en diferentes bienes y servicios. Sin embargo, existen evidencias en diferentes sectores de la necesidad de explorar estos modelos para la creación de una oferta de valor que sea atractiva para los consumidores a lo largo del tiempo, y, al mismo tiempo, rentable para la empresa. La percepción de valor por el consumidor en productos de compra repetitiva, además de por otros factores, cambia a lo largo de los sucesivos momentos de interacción con la categoría de producto. El efecto de estas interacciones se ha considerado en las teorías de formación de hábitos y saciedad, las cuales explican como el nivel habitual de consumo y la saciedad influyen en la formación de utilidad. Con el objetivo de explorar cómo mantener una oferta de valor atractiva a lo largo del tiempo para diferentes segmentos de consumidores, esta tesis examina empíricamente el efecto no lineal de la formación de hábitos y saciedad sobre el valor percibido y los comportamientos poscompra de los clientes recurrentes en un contexto de servicios hedónicos. Se analiza cómo cambia la disposición a pagar respecto a alojamientos turísticos en función del nivel habitual de consumo y la saciedad en un contexto con relación no contractual. Una vez comprobado este efecto, se estudia cómo influye la saciedad sobre el valor percibido y los comportamientos poscompra a lo largo del tiempo en un contexto con relación contractual (servicios por suscripción). Los resultados obtenidos en los diferentes estudios realizados concluyen que la disposición a pagar de un consumidor cambia en función de su nivel habitual de consumo, mostrando un incremento en su disposición a pagar respecto a la anterior visita si se encuentra en fases de sensibilización con el servicio y una disminución en caso de habituación. A su vez, el efecto de la saciedad juega también un papel determinante en la formación de utilidad. Se concluye que los consumidores que experimentan saciedad muestran una menor disposición a pagar y, por tanto, una mayor sensibilidad a los precios. Además, se demuestra que, en modelos de pago por suscripción, esta variable tiene la capacidad de anticipar la decisión de no continuar la suscripción del servicio contratado. Esta tesis contribuye a la literatura previa aportando evidencias empíricas sobre la formación de utilidad en diferentes servicios de uso hedónico, aclarando respecto a la literatura anterior que un precio de referencia no siempre influye de forma lineal y positiva sobre la disposición a pagar. Segundo, amplía el conocimiento sobre cómo la saciedad influencia el valor percibido en servicios con alto riesgo y muestra como esta variable es capaz de anticipar comportamientos desleales, ya que estudiamos tanto la intención de cancelar la suscripción en el corto como en el largo plazo. Finalmente, consideramos que los resultados obtenidos tienen importantes implicaciones, siendo clave incorporar en el análisis del comportamiento del consumidor en productos de compra repetitiva estas dos variables de segmentación de los clientes, el nivel habitual de consumo y la saciedad. [EN]Utility formation models have the ability to predict the benefit that consumers perceive in different goods and services. However, there is evidence in several sectors of the necessity to explore these models for the development of a value offer that is attractive to consumers over time, while also being profitable for the company. The perceived value of consumers in repetitive consumption, along with other factors, undergoes changes over the successive moments of interaction with the product category. The effect of these successive purchases has been considered in habit formation and satiation theories, which explain how the habitual level of consumption and satiation influence utility formation. With the aim of exploring how to maintain an attractive value offer over time for different consumer segments, this dissertation empirically examines the non-linear effect of the habitual level of consumption and satiation formation on perceived value and post-purchase behaviors of repeat customers in a hedonic services context. The study analyzes how willingness to pay for tourism accommodations changes based on habitual level of consumption and satiation in a non-contractual relationship setting. Upon confirming this effect, the study further explores the influence of satiation on perceived value and post-purchase behaviors over time in a contractual relationship setting (subscription retailing sector). The results obtained from the various studies lead to the conclusion that a consumer's willingness to pay is subject to change based on their habitual level of consumption. Specifically, there is an increase in willingness to pay compared to the previous stay if they are in a sensitization phase with the service, and a decrease in the case of habituation. Additionally, the effect of satiation plays a determining role in utility formation. It is concluded that consumers who experience satiation exhibit a lower willingness to pay and, therefore, greater price sensitivity. In turn, it is demonstrated that in subscription retailing, this variable has the ability to anticipate the decision to cancel the contracted subscription. This thesis contributes to previous literature by providing empirical evidence on utility formation in different hedonic services, clarifying that the influence of a reference price on willingness to pay is not always linear and positive, unlike previous literature. Second, it broadens the understanding of how satiation influences perceived value in high-risk services. Furthermore, it demonstrates the capability of this variable to predict unloyalty behaviors, as we examine both short and long-term subscription cancellation. Finally, we consider that the results obtained have important managerial implications being of utmost importance to incorporate these two customer segmentation variables, habitual level of consumption and satiation, into the analysis of consumer behavior in repetitive purchase products

Gut Microbes, Enteropathy and Child Growth: The Role of the Microbiota in the Cycle of Diarrhea and Undernutrition in Peru

Background. The cycle between diarrhea and undernutrition continues to underlie a vast proportion of under-five mortality and is the primary driver of long-term disability among children living in lower and middle-income countries (LMIC). Interventions aimed at reducing childhood stunting have not achieved desired results, highlighting the need for novel research and strategies to target this problem. There is increasing evidence that the gut microbiota are implicated in growth acquisition and sustaining intestinal barrier integrity in a manner that impacts immunity to and consequences of disease; however, these relationships have not yet been examined in large-scale studies of children living in LMIC. Objective. To evaluate relationships between the gut microbial community, child growth, diarrhea and enteric infections (Campylobacter spp) in a birth cohort of 271 children aged 0-24 months in Iquitos, Peru. Methods. Analyses were conducted on children participating in the multi-site cohort study entitled ‘The Interactions of Malnutrition & Enteric Infections: Consequences for Child Health and Development (MAL-ED).’ Data were contributed over two years by mothers and children living in a peri-urban riverine community in Amazonian Peru. Regular home-visits were conducted to ascertain anthropometric indices, illness history, and dietary habits. Length-for-age (LAZ) and weight-for-length (WLZ) Z-scores below - 2 were used to classify stunting and wasting, respectively. Fecal specimens were collected during routine surveillance visits at monthly intervals (N=6004) and additionally during each maternal report of diarrheal symptoms (N=2436). Culture methods, immunoassays and amplification methods were employed according to a unified MAL-ED protocol to identify a panel of over 40 protozoa, bacteria and viruses of public health importance. Microbiota in fecal samples contributed at 6, 12, 18 and 24 months were analyzed by polymerase chain reactions using primers to identify variable regions of bacterial 16S ribosomal RNA genes at the Gordon Laboratory at Washington University. Members were binned into operational taxonomic units (OTU) sharing ≥97% nucleotide sequence identity, producing bacterial communities differentiated at the species level which were then used to generate metrics of maturity (microbiota-for-age Z score; MAZ), diversity (Shannon, Simpson indices) and richness (CHAO1, Faith’s Phylogenetic Diversity). Multivariable regression was used to detect and describe population-averaged associations between microbial metrics, growth acquisition, illness and infection with a generalized estimating equations approach to adjust for within-child correlations over time. Indicator species analysis (ISA) was employed to identify particular gut taxa whose presence and abundance was statistically indicative of phenotypes of interest. Results. Two-thirds of children (67%) were stunted and 9% of children experienced wasting before their 2nd birthday. Microbial diversity and richness increased significantly with age and weaning, and were suppressed by breastmilk exposure. In the first two years of life, we detected a suggestive relationship between microbial maturity and WLZ, but did not observe evidence of associations between microbial maturity, diversity or richness with LAZ in the full cohort. LAZ at birth was significantly associated with MAZ score throughout follow-up (β=0.10, p=0.012) and children born stunted had significantly lower gut microbial diversity and richness (Shannonβ=-0.19, CHAO1 =- 9.75; p-values <0.05) from birth to two years of age. In this subgroup, we additionally observed that children weaned before 24m of age experienced significantly pronounced deficits in microbial diversity and richness acquisition relative to those with continued breastfeeding. Nearly all children (96%) experienced diarrhea during follow-up. Odds of being severely stunted increased by 8% with each additional diarrheal episode throughout the first two years of life (OR=1.08; p<0.001). Cumulative diarrheal frequency, duration and severity were associated with significant reductions in microbial indices (p<0.05), and we observed evidence of enduring deficits beyond 1m after exposure. Children who were born stunted experienced greater insults to microbial diversity per diarrheal episode than those children who were not (Interaction terms: Shannon β =-0.04, p=0.037; Simpson β =-0.01, p=0.032). Time elapsed since last diarrheal episode was associated with recovery of Shannon (β =0.02, p=0.03) and phylogenetic diversity (β =0.11, p<0.01) and we detected evidence that this regeneration process was significantly slower among severely stunted children. Lower diversity and richness were associated with increased subsequent diarrheal incidence; a 1-unit increase in the Shannon and Simpson’s Diversity scales at 6m corresponding to a mean reduction of 1.3 and 3.4 diarrheal episodes from 6-24m of age, respectively. By two years of age, 251 (93%) of all children in the cohort had Campylobacter present in asymptomatic stools, and 221 (82%) experienced infection with diarrhea. Asymptomatic infection was associated with reduced LAZ concurrently and at 3, 6, and 9m thereafter (β=0.02, p<0.01 across all time points). Frequency of Campylobacter- positive diarrhea was associated with a concurrent reduction in -0.03 LAZ (p=0.002), independently from all-cause diarrhea. Asymptomatic Campylobacter infections were associated with changes to the gut microbial environment. Infection was associated with increased microbial diversity and richness metrics, and we identified 21 taxa indicative of being in the highest or lowest quartile of infection from birth to two years of age. Of these, seven indicator species showed suggestive evidence of a link with LAZ concurrently and 1m thereafter. Conclusions. This study provided evidence of associations between the gut microbial community, anthropometric indices, and enteric infections in a population of children experiencing the classical cycle of diarrhea and undernutrition. This is the first study to our knowledge to interrogate these pathways longitudinally in a large, representative sample of infants in LMIC. Our findings generate questions regarding the precise causal mechanisms underlying the observed associations, and should inform subsequent efforts to identify specific and actionable targets to interrupt pathways compounding childhood morbidity and mortality in LMIC