Calibration of multiple-choice questionnaires to assess quantitative indicators

The joint use of two latent factor methods is proposed to assess a measurement instrument for an underlying phenomenon. For this purpose, Rasch analysis is initially used to properly calibrate questionnaires, to discard non informative variables and redundant categories. As a second step, an optimal scaling technique, Nonlinear PCA, is applied to quantify variable categories and to compute a continuous indicator. Specifically, the paper deals with the state of decay of Italian buildings of great architectural and historical interest, which function as a case study . The decay level of the buildings is quantified on the basis of a broad set of observed ordinal variables and the final indicator may be independently used for buildings of future inventory. Overall, similarity and diverse potentiality of the techniques are analyzed and discussed with the purpose of exploring the synergic effect of their combined use.