EZ does it! Extensions of the EZ-diffusion model

In this rejoinder, we address two of Ratcliff's main concerns with respect to the EZ-diffusion model (Ratcliff, in press). First, we introduce \Robust EZ", a mixture model approach to achieve robustness against the presence of response contaminants that might otherwise distort parameter estimates. Second, we discuss an extension of the EZ model that allows the estimation of starting point as an additional parameter. Together with recently developed user{friendly software programs for ¯tting the full dffusion model
(Vandekerckhove & Tuerlinckx, 2007; Voss & Voss, 2007), the development of the EZ model and its extensions are part of a larger effort to make diffusion model analyses accessible to a broader audience, an effort that is long
overdue.