Bob Nardelli's gone, out and finished as the CEO of Home Depot.

Good Riddance.

In the wake of this, lots of people including the Wall Street Journal are decrying his reign as a failure of Six-Sigma quality improvement methods.

In truth, by any financial and operational metric, HD was doing OK, as my friend Vitaliy Katsenelson has pointed out. Six Sigma has probably played some part in this improvement.

Where Nardelli and many of the process junkies out there have failed is in their inability to recognize that in some areas of human endeavor, process improvement just isn't enough. There is noplace where this is truer than in retail sales.

Six-Sigma, like any process methodology, is focused on making a process more and more efficient. It does this by following a process of Defining metrics, Measuring them, Analysing the results, making Improvements, and then Controlling things (DMAIC). Alternately, when new processes are required, it calls for Design, Measure, Analyze, Design, and Verify (DMADV). Either way, it's designed for predictable processes to which there are clearly defined metrics and little variation.

It works great if you're GE manufacturing a million light bulbs.

It works great if you're GE shipping a million light bulbs to a Home Depot.

It works great if you're Home Depot stocking a million light bulbs in warehouses, distributing them to stores, and keeping track of the light bulb inventory.

It is of limited use when selling light bulbs one at a time to a million customers, who have widely different needs, levels of light-bulb expertise and service expectations. You can't approach an improvement in your in-store conduct in the same way as you can measure all those other operational aspects of running it. Businesses and the metrics they use are relatively consistent and predictable. Some companies have even had success using Six Sigma to measure and improve commercial sales because commercial customers are at some level consistent and predictable. But it doesn't work with retail customers. They expect to be treated like individuals, which means that every single customer contact is going to be a new process.

Try to force customers into a process that's convenient to you, and you risk them going elsewhere.

That's what was happenning at Home Depot, as virtually all the personalized aspects of service for which they used to be famous disappeared.

And that's what happened on the board of Home Depot, where Nardelli pretty much told the world "my company, my process, you can leave if you don't like it."

Eventually, they told him to leave.

People like being treated as individuals. A retail business strategy which does not recognize that fact is doomed to failure, and sadly has maligned a methodology which -- when applied judiciously rather than dogmatically -- makes lots of sense even for many retailers.