We report a simple model to include the effect of free-carrier absorption (FCA) in calculating the two-photon absorption (TPA) coefficient, beta, and demonstrate its use in evaluating beta from nonlinear transmission experiments. When only linear absorption and TPA are considered and the experimental analysis is carried out in the usual way, beta is calculated to be 2.0 and 2.7 X 10(-10) m W-1 for TM and TE polarizations, respectively. Including the effect of FCA in the waveguide, the model predicts beta to be 1.5 and 2.0 X 10(-10) m W-1 for TM and TE polarizations, respectively.