During the 1980s using flowcharts was the “in thing” to do. Today, technology has provided us with a much more effective and useful tool: simulation modeling. If a picture is worth a thousand words, then one that logically simulates tasks and collects data has to be worth a million. Simulation models have the capability of considering complex interrelated tasks and structurally projected outcomes in a matter of seconds, providing users with validated, and usually quite reliable, results.
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Author Charles R. Harrell defines simulation as “a means of experimenting with a detailed model of a real system to determine how the system will respond to changes in its structure, environment, or underlying assumptions.” It allows for a better understanding of processes with a goal of improving performance. Simulation modeling provides a means to evaluate, redesign, and measure or quantify customer satisfaction, resource utilization, process streamlining, and time spent.
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Comments
Simulation
I thought, "Harrington- he's sharp. Let's see what he says about simulation." Nice article, but a little disappointing from the standpoint of missing the greatest pitfall. Mentioned that most simualtion produces reliable results. That's true, but these software programs still run on computers and the simulation output is only as good as the input. Very old catchphrase was "Garbage in, garbage out." This is still true, no matter how sophisticated the programming and it remains the grain of salt that must accompany all simulation reports. Second pitfall - the more eye candy in the report/presentation the more the uncertainty regarding the results. Trust, but verify.
Missing the meat
As always, a well considered column and a topic more people need to be aware of. Yet, like most such pieces on simulation, it lacks the necessary details on implementation, and ultimately falls short in terms of its applicability to real-world problems. What exactly is the next step for the reader, who is now impressed with the efficacy of simulation? And where should the reader look to learn more? A stronger column would have delved into the software, which is a critical component of (and often barrier to) simulation, and would have guided readers to additional resources and case studies.
Surprisingly light on value
I agree with the others. More meat needed. Surprisingly light on value for a Harrington piece.
Process Simulation Models Aren't New
I was using process simularion models (visually based, not text) ~20 years ago. Not sure why this article seems to make it sound like some new technology.
Comparing Flowcharts to Simulation Models?
I think using flowcharts in the title and lead paragraph is a bit of a straw man. Most flowcharts are not used for as-is vs. to-be process modeling. Most are used just to document existing processes.
I've been tangentially involved in one simulation study 15 years ago, and as I recall, the it took a lot of work to characterize the process steps in order to build the model. This article makes it seems as though the computer is magic and simulation tools act as an oracle.
I would much rather read a real world case study and an evaluation of which types of processes lend themselves well to simulation. I imagine you would get better results with low-mix, high-volume, or highly automated processes than you would with a high-mix, low-volume, or highly manual processes.
Flowcharts
I agree with Breeze89, what does flow charts have to do with simulation analysis? Isn't this just another quality tool to further the goal of continual improvement of processes, no better or worse than a flow chart just a different application? Solid modeling and simulations have been used in the aerospace and other industries for years, but never has it totally elimnated the need for real world testing. You can control variables, but never eliminate them, after all isn't this why there is real life testing for simulation software as well?
Flowcharts vs Simulation
I'm sorry I hadn't read this until now, and missed these comments. As a simulation analyst and black belt, it is not surprising to me that those in the quality field are making these comments. To say that flowcharting is not used for as-is vs to-be process modeling is the biggest gaff that I have to respond to. I'm not sure what they call value stream mapping (VSM), if not a flowcharting method, and VSM is the most prolific tool in use now for analyzing processes! It's true that simulation has been around for awhile now, but the power of simulation to characterize and experiment with process variables has been nay-sayed for just about as long by the process improvement community. I'm not sure why, but my theory has always been that process owners don't understand their processes well enough to adequately characterize the details of their process, and therefore the process of building a simulation model is difficult. I have been doing manufacturing process analysis for a long time, and almost every time I go into a new facility, I will find details about the process that the engineers and managers of the process never knew. This needs to happen first, and so I'm encouraged by the VSM efforts the manufacturing community has made, but what Mr. Harrington is pointing out is that there is more to life than VSM and flowcharting. By the way, there are about 10 of us currently analyzing a low volume operation (1 ship every 5 years) with much success using simulation, and I have analyzed three robots passing product to each other using simulation, so the applicability of simulation is just up to the imagination of the analyst.
Jim Harrington Responds
Thanks to all of you for your comments. As you can imagine, and as some of you pointed out, a topic like Process Simulation and Flowcharting isn't easily dealt with in a few hundred words. My column was meant as an overview, not a complete treatise on the subject. For more detail related to simulation modeling, and hopefully address some of your questions, please read "Simulation Modeling Methods To Reduce Risk and Increase Performance" by H. James Harrington and Kerim Tumay published by McGraw-Hill.
Thanks
Quality Digest on behalf of H. James Harrington
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