This paper focuses on the macroeconomic impact of introducing new technologies (among which information technologies) when the latter stimulate the relative demand for high-skilled labour. The fact that there is biased technical progress (or at least, that growth has asymmetric effects) is little disputed. Evaluating its effect on unemployment still remains a difficult task. This paper stresses the need to rely on a genuine structural analysis. To clarify some of these issues, we develop a simple analytical framework with two types of labour (high- and low-skilled). This framework is used to distinguish macroeconomic vs structural shocks, and to illustrate the interactions between macroeconomic and structural phenomena as well as their implications for the interpretation of simple mismatch indicators. The framework is next used as a reference setup wherein to evaluate and compare the empirical modelling approaches used by different authors and the results they obtain.