Visual predictive check (VPC) for isoniazid concentration versus time, stratified by NAT2 acetylator status (extensive and intermediate on the left, slow on the right).

The circles represent the original data, the dashed and solid lines are the 5^th, 50^th, and 95^th percentiles of the original data, while the shaded areas are the corresponding 95% confidence intervals for the same percentiles, as predicted by the model.