The data arising from the “HOPE ?WG1 - SSQ - Questionnaire”, gathered on almost 1500 students in 27 sites around Europe, has been analyzed using Rasch models, in order to extract and measure factors inspiring to study physics. In particular, using a Rating Scale Model (Wright & Masters, 1982) and Principal Components Analysis (PCA) of standardized residuals, we identified and measured two main latent traits. These factors, interacting with other personal characteristics such as sex, level of knowledge of physics and so on, may influence performance, decisions, goals and preferences. We applied multilevel logistic regression models with SIMEX correction (Lederer & Küchenhoff, 2006), using the estimated factors as explanatory variables: the results show that these are significant and relevant in explaining the decision to study physics, in association with the level of knowledge of physics and the wish to become a physics teacher. Some possible guidelines for stimulating the decision to study physics arises from this analysis.