Functional and Object Oriented Methodology (FOOM) combines two essential software-engineering paradigms: the functional (process-oriented) approach and the object-oriented (OO) approach. The two main products of FOOM’s analysis phase are two models: a data model in the form of an initial class diagram and a functional model in the form of OO-DFDs (a hierarchy of data flow diagrams including data classes). We evaluate the quality of these models by comparing them with the quality of equivalent analysis models products by Object-Process Methodology (OPM), which also combines the functional and object-oriented approaches, using a unified diagrammatic notation. The comparison is based on a controlled experiment which measured the correctness of the analysis models (specifications) produced by the two methodologies. The results reveal that the quality of models produced by FOOM is better than those produced by OPM.