Statistical Tools in the Joint Analysis of Closed and Open-Ended Questions

The paper aims at presenting some statistical exploratory methods useful in the joint analysis of data collected in a survey, by means of closed and open-ended questions. After a quick review of the main steps necessary for transforming texts in a numerical table, we focus our attention on Lexical Correspondence Analysis. This method is a popular technique for analysing a lexical table obtained by cross-classifying respondents and free responses. As our interest is often in measuring and visualising the association between socio-demographic characteristics and lexical behaviour, the modalities of one or more closed-ended questions are used both for aggregating individuals similar with respect to the considered variables and reducing the sparseness of the lexical table. Dealing with textual data, the effectiveness of a non symmetrical variant of correspondence analysis is introduced. Furthermore, the advantages of asking a free description of the desired product in a conjoint analysis questionnaire is shown, by applying a factorial conjoint analysis with the lexical table as external information.