Declared data and observed data, pros and cons

In this article we address, first of all, the main strengths and weaknesses of the two modalities with which linguistic uses are collected: through the testimony reported by the informants (declared data) or by the observation made by a researcher (observed data). In the second part of the article we consider whether it is possible to develop a way of comparing declared and observed data. We do this based on the analysis of the data from the Survey on Language Use of the Population and the Ofercat, related to the linguistic uses in the stores.