This paper describes further analysis on the evaluation of OO-method Function Points for the Web (OOmFPWeb), a functional size measurement method for Web applications. OOmFPWeb was evaluated using a range of performance-based and perceptionbased variables including productivity, reproducibility, perceived ease of use, perceived usefulness, and intention to use. The evaluation was guided by an evaluation model for information systems design methods, the Method Evaluation Model (MEM). In this work, we present the empirical testing of the MEM to verify the validity of this model in the evaluation of OOmFPWeb. It includes the analysis of causal relationships existing among the different variables of the model. The results show that the MEM is a reliable and valid instrument for evaluating OOmFPWeb but the relationships among productivity, perceived ease of use and intention to use needs to be revised.