There will be no substitute for learning enough about each of the four well-developed process improvement disciplines to be able to provide useful guidance. There's danger in doing so because each has, to one extent or another, taken on the trappings of religious sects -- each has, to many of its practitioners, become the answer. That's "the answer" as in "it doesn't matter what the question is."
To avoid this pitfall, memorize a dictum ascribed to the great architect Louis Sullivan and make it your mantra: Form follows function. When it comes to process optimization, function means knowing how the six parameters of optimization (fixed cost, incremental cost, and so on, as listed above) rank in importance. Once you know how they stack up, you'll know which process improvement discipline -- which form -- is best suited to the situation.
Here's a quick guide -- somewhat oversimplified, but not badly so:
- Lean: Lean's goal is to find and eliminate waste. If your top goal is to reduce incremental cost, it's the right choice. Along the way, lean provides techniques that can help improve quality and reduce cycle time as well.
- Six Sigma: Six Sigma has deep roots in two predecessors -- statistical process control and total quality management. Its primary purpose is reducing variability -- in other words, improving quality. Along the way, it provides useful techniques for reducing incremental cost and cycle time.
- Theory of Constraints: ToC's core mission is to improve throughput. Its core method is to find and eliminate bottlenecks. Its techniques are likely to reduce incremental costs and improve quality along the way.
- Process reengineering: Lean, Six Sigma, and Theory of Constraints all rely on incremental process improvement. Process reengineering is more of a rip-and-replace approach. As such, it is optimized for maximizing consultant revenue. As an IBC, what's most important for you to know about process reengineering is to avoid it whenever you can. Incremental process improvement is almost always the superior choice.
IBC technique No. 5: Process characterization. Before you can improve a process or practice, you have to be able to describe it. IBCs should know how to make use of three complementary descriptions: black-box analysis, white-box analysis, and a cheesy but very effective trick.
Black-box analysis doesn't care how a business function gets the work done. All it cares about is what the process does. Black-box analysis lists its: