Bizagi simulated process completion times appear not to be consistent with Queuing Theory
Firstly let congratulate Bizagi on their addition of simulation to Modeler 2.5. I teach Business Process Management in university. This will be a great asset to students.
I ran some tests on the new simulation feature, and I wanted to share the results. I chose the simplest process, one with a single task and single actor.
I assumed both job interarrival and services times are random (follow a (Negative) Exponential distribution), with just one actor. In Queuing Theory this is called an M/M/1 queue. I set the average interarrival time at 5 min and average service time at 4 min. Queuing Theory predicts the following:
- Resource Utilization Factor = 80% ,
- Average completion time = 20 min, and
- Average waiting time = 16 min.
However the Bizagi simulation engine seems to produce different results. I ran the simulation for 100000 instances, which should be more than enough to reach a steady state. I obtained the
- Resource Utilization Factor = 81.13%
- Average completion time = 21.38 min, and
- Average waiting time = 17.34 min.
IMHO, this is not close enough to the theoretical result, given the large number of iterations. I invite others to run the test to replicate the results. Is there something I have overlooked?
FYI, I have attached screen shots and model.