1 3. Process Flow Measures A hospital emergency room (ER) is currently organized so that all patients register through an initial check-in process. At his or her turn, each patient is seen by a doctor and then exits the process with a prescription. Currently 55 people per hour arrive at the ER. On average, 7 people are waiting to be registered and 34 are registered and waiting to see a doctor. The registration process takes, on average, 2 minutes per patient. 90% of patients spend 5 minutes with a physician, get a simple prescription and leave. The rest of the patients spend 30 minutes with a physician and are admitted to the hospital. On average, how long does a patient spend in the ER? Assume the process to be stable; that is, average inflow rate equals average outflow rate. Problem 3.4 MBPF

2 3. Process Flow Measures Directions o) Draw the flow process chart b) On average how long a patient spend in ER? c) On average how many patients are in ER? Hints: Compute flow time in buffer 1 Compute average activity time of Doctor Compute the average flow time in this process Compute average flow time for a simple prescription patient Compute average flow time for a potential admission patient Compute number of patients in Doctor activity Compute the average number of patients in the process.

3 3. Process Flow Measures T PA = = T D =.9(5)+.1(30) = 7.5 T SP = = 51.7 T P =.1(76.7)+.9(51.7) = 54.2 Flow Time

4 3. Process Flow Measures 6.9 Inventory 1.8

5 3. Process Flow Measures 49.7 I = 49.7, R = 55. Is our T= 54.2 correct? RT= I R = 55/60 = minutes RT = I  T=I/R = 49.7/ = 54.2 Recheck The Little’s Law