Figure 9: Gamma function basics. Illustration of consequences of using several sequential pools in representing a clinical category. Results for a single pool (a), two pools (), three pools (), four pools (), and eight pools () are given, showing in each case the value of the state variable for the final pool in the sequence. For pools, the rate constant has been set to give the same mean overall transit time of day (indicated by ■). For each curve, the maximum value (●) denotes the most probable overall transit time.