Figure 4

Modeling diagnostics The points in graphs of the standardized residuals versus the log _e standard concentrations (A) and the standardized residuals versus the estimated log _e spot intensities (B) are reasonably well behaved, showing no strong systematic trends or deviations from the zero line. These indicate that the four-parameter logistic model is acceptable, that subsequent statistical inferences are reasonable, but that a better model may exist in another model family.