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Publicações

Publicações por Vera Miguéis

2023

Overlap in Automatic Root Cause Analysis in Manufacturing: An Information Theory-Based Approach

Autores
Oliveira, EE; Migueis, VL; Borges, JL;

Publicação
APPLIED SCIENCES-BASEL

Abstract
Automatic Root Cause Analysis solutions aid analysts in finding problems' root causes by using automatic data analysis. When trying to locate the root cause of a problem in a manufacturing process, an issue-denominated overlap can occur. Overlap can impede automated diagnosis using algorithms, as the data make it impossible to discern the influence of each machine on the quality of products. This paper proposes a new measure of overlap based on an information theory concept called Positive Mutual Information. This new measure allows for a more detailed analysis. A new approach is developed for automatically finding the root causes of problems when overlap occurs. A visualization that depicts overlapped locations is also proposed to ease practitioners' analysis. The proposed solution is validated in simulated and real case-study data. Compared to previous solutions, the proposed approach improves the capacity to pinpoint a problem's root causes.

2011

Mining Customer Loyalty Card Programs: The Improvement of Service Levels Enabled by Innovative Segmentation and Promotions Design

Autores
Migueis, VL; Camanho, AS; Falcao e Cunha, JFE;

Publicação
EXPLORING SERVICES SCIENCE

Abstract
A good relationship between companies and customers is a crucial factor of competitiveness. The improvement of service levels has become a key issue to develop and maintain a loyal relationship with customers. This paper proposes a method for promotions design for retailing companies, based on knowledge extraction from transactions records of customer loyalty cards, aiming to improve service levels and increase sales. At first, customers are segmented using k-means and then the segments' profile is characterized according to the rules extracted from a decision tree. This is followed by the identification of product associations within segments, which can base the identification of the products most suitable for customized promotions. The research reported is done in collaboration with an European retailing company.

2012

Modeling partial customer churn: On the value of first product-category purchase sequences

Autores
Migueis, VL; Van den Poel, D; Camanho, AS; Falcao e Cunha, JFE;

Publicação
EXPERT SYSTEMS WITH APPLICATIONS

Abstract
Retaining customers has been considered one of the most critical challenges among those included in Customer Relationship Management (CRM), particularly in the grocery retail sector. In this context, an accurate prediction whether or not a customer will leave the company, i.e. churn prediction, is crucial for companies to conduct effective retention campaigns. This paper proposes to include in partial churn detection models the succession of first products' categories purchased as a proxy of the state of trust and demand maturity of a customer towards a company in grocery retailing. Motivated by the importance of the first impressions and risks experienced recently on the current state of the relationship, we model the first purchase succession in chronological order as well as in reverse order, respectively. Due to the variable relevance of the first customer-company interactions and of the most recent interactions, these two variables are modeled by considering a variable length of the sequence. In this study we use logistic regression as the classification technique. A real sample of approximately 75,000 new customers taken from the data warehouse of a European retail company is used to test the proposed models. The area under the receiver operating characteristic curve and 1%, 5% and 10% percentiles lift are used to assess the performance of the partial-churn prediction models. The empirical results reveal that both proposed models outperform the standard RFM model.

2012

Predicting partial customer churn using Markov for discrimination for modeling first purchase sequences

Autores
Migueis, VL; Van den Poel, D; Camanho, AS; Falcao e Cunha, JFE;

Publicação
ADVANCES IN DATA ANALYSIS AND CLASSIFICATION

Abstract
Currently, in order to remain competitive companies are adopting customer centered strategies and consequently customer relationship management is gaining increasing importance. In this context, customer retention deserves particular attention. This paper proposes a model for partial churn detection in the retail grocery sector that includes as a predictor the similarity of the products' first purchase sequence with churner and non-churner sequences. The sequence of first purchase events is modeled using Markov for discrimination. Two classification techniques are used in the empirical study: logistic regression and random forests. A real sample of approximately 95,000 new customers is analyzed taken from the data warehouse of a European retailing company. The empirical results reveal the relevance of the inclusion of a products' sequence likelihood in partial churn prediction models, as well as the supremacy of logistic regression when compared with random forests.

2012

Productivity change and innovation in Norwegian electricity distribution companies

Autores
Migueis, VL; Camanho, AS; Bjorndal, E; Bjorndal, M;

Publicação
JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY

Abstract
Regulators of electricity distribution networks have typically applied Data Envelopment Analysis (DEA) to cross-section data for benchmarking purposes. However, the use of panel data to analyse the impact of regulatory policies on productivity change over time is less frequent. The main purpose of this paper is to construct a Malmquist productivity index to examine the recent productivity change experienced by Norwegian distribution companies between 2004 and 2007. The Malmquist index is decomposed in order to explore the sources of productivity change, and to identify the innovator companies that pushed the frontier forward each year. The input and output variables considered are those used by the Norwegian regulator. In order to reflect appropriately the exogenous conditions where the companies operate, the efficiency model used in this paper incorporates geography variables as outputs of the DEA model. Unlike the model used by the regulator, we included virtual weight restrictions in the DEA formulation to correct the biases in the DEA results that may be associated to a judicious choice of weights by some of the companies. Journal of the Operational Research Society (2012) 63, 982-990. doi: 10.1057/jors.2011.82 Published online 26 October 2011

2012

Customer data mining for lifestyle segmentation

Autores
Migueis, VL; Camanho, AS; Falcao e Cunha, JFE;

Publicação
EXPERT SYSTEMS WITH APPLICATIONS

Abstract
A good relationship between companies and customers is a crucial factor of competitiveness. Market segmentation is a key issue for companies to develop and maintain loyal relationships with customers as well as to promote the increase of company sales. This paper proposes a method for market segmentation in retailing based on customers' lifestyle, supported by information extracted from a large transactional database. A set of typical shopping baskets are mined from the database, using a variable clustering algorithm, and these are used to infer customers lifestyle. Customers are assigned to a lifestyle segment based on their purchases history. This study is done in collaboration with an European retailing company.

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