This paper describes a data model for speech assessment tests with subjects. The aim of the proposed model is to obtain a description of the most important parameters which influence the outcome of speech assessment tests. Such a model enables a more controlled design of new test methods and the modification of existing methods. The proposed data model is divided into two parts: a description of the test methodology and a description of the used data. In order to verify the data model and to create software tools for speech assessment the proposed model was implemented as a software package.