Understanding influence in behavioral data has become increasingly important in analyzing the cause and effect of human behaviors under various scenarios. Influence modeling enables us to learn not only how human behaviors drive the diffusion of memes spread in different kinds of networks, but also the chain reactions evolve in the sequential behaviors of people. In this thesis, I propose to investigate into appropriate probabilistic models for efficiently and effectively modeling influence, and the applications and extensions of the proposed models to analyze behavioral data in computational sustainability and information search. One fundamental problem in influence modeling is the learning of the degree of influence between individuals, which we called social infectivity. In the first part of this work, we study how to efficient and effective learn social infectivity in diffusion phenomenon in social networks and other applications. We replace the pairwise infectivity in the multidimensional Hawkes processes with linear combinations of those time-varying features, and optimize the associated coefficients with lasso regularization on coefficients. In the second part of this work, we investigate the modeling of influence between marked events in the application of energy consumption, which tracks the diffusion of mixed daily routines of household members. Specifically, we leverage temporal and energy consumption information recorded by smart meters in households for influence modeling, through a novel probabilistic model that combines marked point processes with topic models. The learned influence is supposed to reveal the sequential appliance usage pattern of household members, and thereby helps address the problem of energy disaggregation. In the third part of this work, we investigate a complex influence modeling scenario which requires simultaneous learning of both infectivity and influence existence. Specifically, we study the modeling of influence in search behaviors, where the influence tracks the diffusion of mixed search intents of search engine users in information search. We leverage temporal and textual information in query logs for influence modeling, through a novel probabilistic model that combines point processes with topic models. The learned influence is supposed to link queries that serve for the same formation need, and thereby helps address the problem of search task identification. The modeling of influence with the Markov property also help us to understand the chain reaction in the interaction of search engine users with query auto-completion (QAC) engine within each query session. The fourth part of this work studies how a user's present interaction with a QAC engine influences his/her interaction in the next step. We propose a novel probabilistic model based on Markov processes, which leverage such influence in the prediction of users' click choices of suggested queries of QAC engines, and accordingly improve the suggestions to better satisfy users' search intents. In the fifth part of this work, we study the mutual influence between users' behaviors on query auto-completion (QAC) logs and normal click logs across different query sessions. We propose a probabilistic model to explore the correlation between user' behavior patterns on QAC and click logs, and expect to capture the mutual influence between users' behaviors in QAC and click sessions.

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In recent years, the Buy Now Pay Later service has spread across the e-commerce industry, and credit modeling is inevitable of interest for related companies to predict the default rate of the customers. The traditional data used in such models are financial bureaus which include credit records bought from external financial institutions. However, external financial bureaus are not ensured high quality, are expensive , and a large number of the population could lack bank records in some markets. In terms of ethics, the financial bureau can lead to discrimination between the traditional asset holder and the young generation, as well as the developed and developing countries for an international company. Instead of comparing different classification methods, this paper investigates the feasibility and usage of click behavior(CB) data from the customer in credit modeling by carrying out feature engineering and conducting comparative experiments. The study demonstrates whether and how we can use CB data as a new data source and the restrictions. The results show that despite the CB data doesn’t impact enhancing the performance of the traditional model, the CB data model has sufficient performance for orders with CB data and weak performance for orders in general due to the hitting rate of the CB data. The CB not only has predictability on orders placed in the shopping app but also on orders placed from other sources such as the website for the same customer. Besides, the CB data perform better on specific customer segments, including new customers, shopping app customers, and high order amount customers. Adding such segment indicators can improve the performance of the CB model. In addition, the best click behavioral feature set is selected by using correlation analysis and the Reverse Feature Elimination method. / Under de senaste åren har så kallade “Buy now, Pay later” (köp nu, betala senare) tjänster spridit sig över e-handelsbranschen, och kreditmodellering är oundvikligen av intresse för att förutsäga kundernas risk för fallissemang. De traditionella uppgifterna som används i sådana modeller kommer från till stor del från externa källor, såsom kreditupplysningar köpta från externa finansinstitut. Men externa finansbyråer har tillkortakommanden. Exempelvis kan kvaliteten vara otillräcklig, priset för tjänsten kan vara högt och ett stort antal av befolkningen kan sakna uppgifter. Från ett etiskt perspektiv kan användandet av denna data leda till diskriminering mellan den traditionella tillgångsinnehavaren och den yngre generationen, såväl som mellan de utvecklade länderna och utvecklingsländerna för ett internationellt företag. Istället för att jämföra olika klassificeringsmetoder, undersöker detta arbete genomförbarheten och användningsbarheten av att använda kunders klickbeteendedata (KB) i kreditmodellering genom att utföra variabelutveckling och jämförande experiment. Studien visar om och hur vi kan använda KB-data som en ny datakälla och vilka begränsningarna som medföljer. Resultaten visar att variabler baserad på KB-data inte har signifikant påverkan på kreditmodellers prestanda i allmänhet. Dock så har de en prediktiv förmåga när modeller tränas endast på ordrar där KB-data finns tillgängligt. Dessutom går studien igenom vilka kundsegment som främst gynnas av KB-data såsom nya kunder, kunder som gjort köp via Klarnas shopping app samt kunder med som gör stora köp. Att lägga till sådana segmentindikatorer kan förbättra KB-modellers prestanda.

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This report is about examining the fields of machine learning and digital marketing, using machine learning as a tool to predict churn in a new domain of companies that do not track their customers extensively, i.e where behaviour data is discontinuous.  To predict churn relatively simple out of the box models, such as support vector machines and random forests, are used to achieve an acceptable outcome. To be on par with the models used for churn prediction in subscription based services, this report concludes that more research has to be done using more effective evaluation metrics. Finally it is presented how these discoveries can be commercialized and the business related benefits of using churn prediction for the employer Sellpy. / Denna rapport handlar om att utforska fälten maskininlärning och digital marknadsföring, genom att använda maskininlärning som ett redskap för att förutspå churn i en typ av företag med diskontinuerlig beteendedata. För att förutspå churn finns relativt simpla "out of the box"-modeller, som support vector machines och random forests, som används för att nå acceptabla resultat. För att nå liknande resultat som i arbeten där churn utförs på kontinuerlig beteendedata konstaterar denna rapport att framtida arbeten forska på vilka utvärderingsmetriker som är mest lämpade. I rapporten presenteras också hur dessa upptäckter kan kommersialiseras och hur företaget Sellpy kan tjäna på att förutspå churn.