Assessing the Number of Components in Mixture Models: a Review.

Despite the widespread application of finite mixture models, the decision of how many classes are required to adequately represent the data is, according to many authors, an important, but unsolved issue. This work aims to review, describe and organize the available approaches designed to help the selection of the adequate number of mixture components (including Monte Carlo test procedures, information criteria and classification-based criteria); we also provide some published simulation results about their relative performance, with the purpose of identifying the scenarios where each criterion is more effective (adequate).Finite mixture; number of mixture components; information criteria; simulation studies.

Comparing alternative instruments to measure service quality in higher education

The purpose of this work is to examine the performance of five alternative measures of service quality in the high education sector – SERVQUAL (Service Quality), Importance-weighted SERVQUAL, SERVPERF (Service Performance), Importance-weighted SERVPERF and HedPERF (Higher Education Performance). We aim at determining which instrument has the superior measurement capability. Data were collected by means of a structured questionnaire containing perception items enhanced from the SERVPERF and HEdPERF scales and expectation items from the SERVQUAL scale, both modified to fit into the higher education sector. The first draft of the questionnaire was subject to a pilot testing through a focus group and an expert evaluation. Data were gathered from a 360 students’ sample of a Portuguese university in Lisbon. Scales were compared in terms of unidimensionality, reliability, validity and explained variance. Managerial conclusions were also drawn.service quality scales; higher education; reliability

Examining the segment retention problem for the “Group Satellite” case

The purpose of this work is to determine how well, criteria designed to help the selection of the adequate number of market segments, perform in recovering small niche segments, in mixture regressions of normal data, with experimental data. The simulation experiment compares several segment retention criteria, including information criteria and classification-based criteria. We also address the impact of distributional misspecification on segment retention criteria success rates. This study shows that Akaike’s Information criterion with penalty factors of 3 and 4, rather than the traditional value of 2, are the best segment retention criteria to use in recovering small niche segments. Although these criteria were designed for the specific context of mixture models, they are rarely applied in the marketing literature.Information criteria; Latent Class Segmentation.

Comparing Airport regulation in Europe: Is there need for a European Regulator?

This paper provides an overview of how the major airports are regulated in Europe. In order to eliminate the potential of airports to exercise market power and protect the public interest, it has become increasingly necessary to set a common regulatory framework. We intend to discuss the need of a single regulator in Europe to monitor or establish the quality of service and the charges practiced by the airports, to ensure cost-relatedness, transparency and non-discrimination. The existing regulatory approaches regarding aeronautical charges and their economic implications are also analyzed. We propose the creation of a European Observatory for this sector.airports, economic regulation, European Observatory

Democracy and Economic Development: a Fuzzy Classification Approach

The aim of this work is to (1) analyse whether countries differ on political indicators (democracy, rule of law, government effectiveness and corruption) and (2) study whether countries with different political profiles are associated with different levels of economic, human development and gender-related development indicators. Using a fuzzy classification approach (fuzzy k-means algorithm), we propose a typology of 124 countries based on 10 political variables. Six segments are identified; these political groups implicate the access to different levels of economic and human development. In this study evidence of a positive but not perfect relationship between democracy and economic and human development is observed, thus presenting new insights for the understanding of the heterogeneity of behaviors relatively to political indicators.Democracy, Economic Development, Fuzzy k-means

Aspectos Metodológicos da Segmentação de Mercado: Base de Segmentação e Métodos de Classificação

This work provides a broad review of the past literature on market segmentation, focusing on a discussion of proposed bases and classification methods. Multiple segmentation bases are detached, organized according to two axes - observable/ unobservable, general/ specific of the product and evaluated according to some criteria that must be satisfied for an effective segmentation: identifiability, substantiality, accessibility, stability, actionability and responsiveness Classification methods grouped in three classes - nonoverlapping, overlapping and fuzzy, according to the format of the partition matrix they provide.market segmentation, effective segmentation, segmentation bases, classification analysis

Identifying small market segments with mixture regression models

The purpose of this work is to determine how well criteria designed to help the selection of the adequate number of market segments perform in recovering small niche market segments, in mixture regressions of normal data. As in real world data the true number of market segments is unknown, the results of this study are based on experimental data. The simulation experiment compares 27 segment retention criteria, comprising 14 information criteria and 13 classification-based criteria. The results reveal that AIC3, AIC4, HQ, BIC, CAIC, ICLBIC and ICOMPLBIC are the best criteria in recovering small niche segments and encourage its use.peer-reviewe

themes in online reviews

Brochado, A., Rita, P., Oliveira, C., & Oliveira, F. (2019). Airline passengers’ perceptions of service quality: themes in online reviews. International Journal of Contemporary Hospitality Management, 31(2), 855-873. https://doi.org/10.1108/IJCHM-09-2017-0572Purpose: This paper aims to identify the main themes shared in online reviews by airline travellers, as well as which of these themes were linked with higher and lower value for money ratings. Design/methodology/approach: The research used mixed content analyses (i.e. quantitative and qualitative) to examine 1,200 reviews of six airline companies shared by airline travellers in a social media platform. Findings: The analyses revealed nine themes in descriptions of airline travel experiences. These are the core services during “flights”, “airport” operations, crew and ground “staff”, ticket “classes”, “seats”, inflight “services”, “entertainment”, overall experiences of “airlines” and post-purchase recommendations of with which companies to “fly”. Low value for money ratings are linked with the “airport” and “flights” themes. Originality/value: The results offer useful insights into airline travellers’ overall experiences based on social media information and facilitate the identification of the main themes linked with different value for money ratings.authorsversionpublishe

The islands of the senses of Cape Verde

Oliveira, C., Brochado, A., Moro, S., & Rita, P. (2019). Consumer perception of tourist experience through online reviews: The islands of the senses of Cape Verde. Worldwide Hospitality and Tourism Themes, 11(6), 696-717. https://doi.org/10.1108/WHATT-09-2019-0052Purpose: Overall, there is a lack of research using online reviews as a proxy of customer experience when addressing the study of tourism in island destinations. Design/methodology/approach: The current investigation aims to fill this gap by focussing on an African small island developing states, i.e. Cape Verde. This paper reports of tourist reviews extracted from TripAdvisor from “two islands of the senses” as coined by this archipelago’s national tourism organization, specifically Santo Antão and Fogo islands. The data analysis was performed through Leximancer software to generate concepts out of words, followed by themes. Findings: The present research focussed on experiences in island tourism to identify their main dimensions based on visitors’ narratives in online reviews. The obtained results are of potential value to the literature by contributing to a better understanding of tourist experience in the context of tourism in islands in an understudied country, Cape Verde. Originality/value: Results are presented and object of discussion vis-à-vis scientific literature and conclusions put forward in this journal paper.authorsversionpublishe

Post-Transcriptional Control of RNA Expression in Cancer

Approximately 80% of the human genome contains functional DNA, including protein coding genes, non-protein coding regulatory DNA elements and non-coding RNAs (ncRNAs). An altered transcriptional signature is not only a cause, but also a consequence of the characteristics known as the hallmarks of cancer, such as sustained proliferation, replicative immortality, evasion of growth suppression and apoptotic signals, angiogenesis, invasion, metastasis, evasion of immune destruction and metabolic re-wiring. Post-transcriptional events play a major role in determining this signature, which is evidenced by the fact that alternative RNA splicing takes place in more than half of the human genes, and, among protein coding genes, more than 60% contain at least one conserved miRNA-binding site. In this chapter, we will discuss the involvement of post-transcriptional events, such as RNA processing, the action of non-coding RNAs and RNA decay in cancer development, and how their machinery may be used in cancer diagnosis and treatment