Practical Application

Looking at a practical application, we can determine that a normal person eats approximately 3 meals per day and possibly 2 snacks for a total of 35 meals per week. If we survey the current state of the client and we rate each meal on a scale of 1-10, we determine that anything rated less than a 8 is an "error" in how we are eating. We may note that they are eating at a level of between 4-5-6 for most meals per week or approximately 68% error rate, which is likely too high to achieve optimal health and weight markers. We may also note that they eat at a level of 2-3 and 7-9 approximately 27% of the time, and either a 1 (very bad) or a 10 (very good) only 5% of the time. This is a pretty normal bell curve distribution. 

Established practices have shown that at least 80% compliance in the consumption of healthy meals is required to achieve successful results, and possibly as much as 90% to achieve more optimal goals, meaning we need to have an error rate of no more than 10-20%.  

In the Six Sigma world, we can look at the curve as a visual representation of error rates with a goal of achieving 80% compliance, or 28 meals/snacks per week rated at 8+ and only 7 meals under an 8 rating, which would be a theoretical error rate of 20.0%. To put this in Six Sigma jargon, this would equate to a an error factor of 200,000 per 1,000,000 meals which would take almost 550 years to consume. As such, we have to deal in smaller volume defects and in this case, a target theoretical error rate of 2.34 sigma, rather than 6 sigma based on a normal bell curve distribution.

Six Sigma or 6 standard deviations is not a constant, but rather, a theoretical goal that is so small, it is considered almost perfect.  In reality, when it comes to optimal health and longevity, often Three Sigma or 3 standard deviations could be more than adequate to achieve excellent health in many aspects of measuring defects that the body throws off.   This is especially true as it applies to the population averages, but striving for perfection or Six Sigma (no defects) is always the goal that keeps you on track. For more serious errors or defects that the body may throw off we may need to consider ranges between 2.5 - 6 sigma to achieve health and wellness.