Statistical tools in the joint analysis of closed and open-ended questions

The paper aims at presenting some statistical exploratory methods useful in jointly analysing data collected in a survey, by means of open and close 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, a popular technique for analysing a lexical table obtained by cross-classifying respondents and free responses. As the interest is often in measuring and visualising the association between socio-demographic characteristics and lexical behaviour, the modalities of one or more close 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.