I am confusing about something related to the inversion and identification of the models that describe the changes in blood flow and blood oxygenation during brain activation (e.g: Balloon hemodynamic model (Friston 2002), Metabolic hemodynamic model MHM (Sotero 2007)) from real BOLD measurement (BOLD percent signal change %), now The measurement equation of the Balloon hemodynamic model which represent the BOLD signal is V0[ k1(1 - q) + k2(1-q/v) + k3(1-v)] (V0[a1(1-q) - a2(1-v)] for MHM), what confusing me: when we try to calibrate (identification) the previously cited models, is the measurement equation take the same form whether we use the BOLD signal or the BOLD percent signal change %?