While there are statistically significant benefits to using 4PL+C to analyze complete curves, the improvement is even more evident for incomplete curves. We obtained incomplete curves by removing data corresponding to the two highest concentrations of the simulated completed curves (Fig. ). Removing this data increases the MSE of all parameter estimates (Table ??). While the increase in MSE is approximately four-fold for the standard 4PL procedure, the increase is subtle for 4PL+C; using the positive control appears to mostly compensate for losing data points at the highest concentrations. Because 3PLFB also uses the controls to set R b , this procedure also compensates for the loss of these data points and the precision is similar to 4PL+C. 1.8 (9.0E-2) 3.9 (1.6E-1) 3.8 (1.4E-1) x 50 1.4E-3 (2.9E-5) 8.2E-3 (3.0E-4) 1.4E-3 (5.1E-5) H 5.8E-3 (2.5E-4) 2.1E-2 (7.8E-4) 6.0E-3 (2.3E-4)