Classical Test Theory (CTT) has been the main psychometrical model forconstructing and analysing tests. However CTT limitations have given place to alternative models, such as the Rasch Model (RM), which allows ?given a good fit? conjoint measurement of persons anditems on the same dimension, or construct. The various advantages of the RM are presented following a detailed example? the analysis of the Mathematics Test (MT) constructed by the authors. The MT is used to illustrate the advantages of the RM both for collective assessment and for individual diagnosis; the main techniques used in the analysis are also introduced.

Se describe el modelo de Rasch para la interpretaci?n de los test com alternativa a otros modelos habitualmente empleados. Las ventajas de dicho modelo se analizan en el ejemplo del Test de Matem?ticas (TM) construido por los autores.