Comparison of different panels sorting tasks with hierarchical multiple factor analysis

Hierarchical multiple factor analysis is a suitable tool for giving account of the evaluation of a same set of items by hierarchically structured sets of individuals. This method is applied to compare trained and non-trained panels in wine hall tests. Every panellist has to categorize the wines in clusters, describe them with free descriptive words and also give a hedonic score. Data coding leads to a wine × individual evaluation table in which the columns present a hierarchical structure. Hierarchical multiple factor analysis allows for exploring and visualizing the observed variability among both wines and panellists. Visualizing tools are also offered to evaluate the similarity between panels and sets of panels.Postprint (author’s final draft

Comparaison des structures induites sur un ensemble de réponses ouvertes par le choix de l’unité statistique

Le choix de l’unité statistique de segmentation du corpus, ainsi que celui de la distance entre les réponses, induit une structure sur l’ensemble des réponses. Nous proposons d’appliquer une méthodologie statistique, l’analyse factorielle multiple pour tableaux de contingence, AFMTC, pour, d’une part, comparer les structures induites sur un même corpus par différentes unités statistiques et, d’autre part, définir une distance entre textes capable de prendre en compte différentes unités et de profiter ainsi de l’information véhiculée par chacune d’elles. Pour présenter cette méthodologie, généralisation de l’analyse des correspondances aux tableaux de contingence multiples, on utilise une enquête auprès de femmes divorcées qui comporte une question ouverte sur les raisons de leur divorce. Comparison between the structures that are induced by the choice of the statistical unitThe election of the statistical unit, as well as that of the distance between responses, induces a structure on the whole of the responses. We propose to apply a statistical methodology, the multiple factorial analysis for contingency table, MFACT, in order to, on the one hand, compare the structures induced on a same corpus by different statistical units and, on the other hand, define a distance between texts able to take into account different units and so take advantage of the information that they convey. To present this methodology, a generalisation of correspondence analysis to multiple contingency tables, we use a survey carried out on divorced women, that includes an open-ended question about the reasons of their divorce

Napping combined with ultra-flash profiling, a quality tool in food industry. Application to Catalan and Chilean wines

The characterization of wines by experts requires short-time consuming hall tests procedures. Thus, holistic methods have been developed such as napping which, for each expert, collects a bi-dimensional configuration of the products in only one session. Ultra-flash profiling, a spontaneous descriptive technique, offers a complement that allows for interpreting the results.Postprint (published version

Mesurem els mots? L'anàlisi estadística de textos

En las encuestas por cuestionario, es usual introducir preguntas abiertas. En los estudios de consumo, los expertos y/o consumidores evalúan los productos mediante una puntuación y, conjuntamente, un comentario libre. El análisis estadístico de este tipo de datos, llamados datos mixtos, requiere de métodos específicos. Proponemos aquí emplear una metodología que combina el análisis factorial múltiple clásico y el análisis factorial múltiple para tablas de contingencia. Esta extensión del AFM permite tratar globalmente tablas léxicas, creadas a partir de las respuestas textuales, y tablas cuantitativas y categóricas. Presentamos la metodología apoyándonos en datos recogidos en la evaluación de dos conjuntos de vinos. El análisis sensorial constituye en efecto un área de aplicación privilegiada, dado que los expertos y consumidores desean frecuentemente complementar los clásicos perfiles sensoriales con descripciones libres que traducen más fielmente sus percepciones. La metodología se puede emplear también en el tratamiento de datos de encuesta, cuando se aborda una problemática con una batería de preguntas cerradas y de preguntas abiertas.Postprint (published version

Untangling the influence of several contextual variables on the respondents‘lexical choices. A statistical approach

This work proposes an original textual statistical method to uncover the relationships between opinions, expressed as free-text answers, and respondents’ characteristics. This method also identifies the specific links between each characteristic and certain words used in these answers. Promising results are obtained as shown by an application to real data collected to know what health means for non-experts, essential knowledge for effective public health interventions

Correspondence Analysis on Generalised Aggregated Lexical Tables (CA-GALT) in the FactoMineR Package

Abstract Correspondence analysis on generalised aggregated lexical tables (CA-GALT) is a method that generalizes classical CA-ALT to the case of several quantitative, categorical and mixed variables. It aims to establish a typology of the external variables and a typology of the events from their mutual relationships. In order to do so, the influence of external variables on the lexical choices is untangled cancelling the associations among them, and to avoid the instability issued from multicollinearity, they are substituted by their principal components. The CaGalt function, implemented in the FactoMineR package, provides numerous numerical and graphical outputs. Confidence ellipses are also provided to validate and improve the representation of words and variables. Although this methodology was developed mainly to give an answer to the problem of analyzing open-ended questions, it can be applied to any kind of frequency/contingency table with external variables

Comparison of the reproducibility of a trained and an untrained panel in a napping evaluation

Postprint (published version

Napping: una metodologia per a l'avaluació sensorial de vins : aplicació a l'estudi de vins catalans i xilens

Es presenta en aquest article un nova metodologia per a l'avaluació sensorial de productes alimentaris d'una manera global, no condicionada a un determinat conjunt de descriptors de notes específiques del producte, sinó a una percepció global del producte. El procediment es fonamenta en la disposició de les mostres tastades sobre unes estovalles (napping) d'acord amb la seva similitud. El tractament estadístic dels resultats, les rotacions procrustes i l'anàlisi factorial múltiple permeten l'obtenció d'informació tant de les mostres com dels tastadors. En l'article es presenta l'experiència realitzada a la seu de l'Institut d'Estudis Catalans, organitzada per l'Associació Catalana de Ciències de l'Alimentació (ACCA), l'Agrocampus de Rennes, la Universitat Politècnica de Catalunya, l'Institut Químic de Sarrià i amb el suport de l'ambaixada de França, relativa a la degustació, de divuit tastadors, de diferents vins catalans i xilens.A new methodology for sensory evaluation of food products is presented in this paper. Instead the conventional descriptive procedure, the judge response is an holistic personal criteria about each sample, represented as coordinates on a tablecloth (napping). Procrustean rotations and multiple factor analysis allow to achieve the relevant information, both related to samples and judges. The experience of a tasting session developed in the Institut d’Estudis Catalans, supported by the Associació Catalana de Ciències de l’Alimentació (ACCA), Agrocampus de Rennes, Universitat Politècnica de Catalunya, Institut Químic de Sarrià and the France Embassy in Barcelona, samples of Catalan and Chilean wines is presented, as well as the results of the analysis of responses of eighteen member’s jury

Correspondence analysis on generalised aggregated lexical tables (CA-GALT) in the FactoMineR package

Correspondence analysis on generalised aggregated lexical tables (CA-GALT) is a method that generalizes classical CA-ALT to the case of several quantitative, categorical and mixed variables. It aims to establish a typology of the external variables and a typology of the events from their mutual relationships. In order to do so, the influence of external variables on the lexical choices is untangled cancelling the associations among them, and to avoid the instability issued from multicollinearity, they are substituted by their principal components. The CaGalt function, implemented in the FactoMineR package, provides numerous numerical and graphical outputs. Confidence ellipses are also provided to validate and improve the representation of words and variables. Although this methodology was developed mainly to give an answer to the problem of analyzing open-ended questions, it can be applied to any kind of frequency/contingency table with external variables.Peer ReviewedPostprint (published version