"The devil is in the details"
You achieve quality when you control the important details.
Many things can influence a result. However, some details are more important than others.
If you can select the details that matter the most and focus on them you will achieve quality.
This applies to athletes, manufacturing companies and everyone else.
Six Sigma can help you improve quality
Six Sigma has much in common with Lean, and involves strong customer focus, process understanding and focus on measurements rather than intuition. Six Sigma includes statistical tools to understand variation and identify the most important factors; the critical factors. By controlling the variation of critical factors you will achieve the wanted result.
What is a critical factor?
For an athlete, this may be sufficient sleep and rest, proper food at the right time, or repeating a detail you need to improve. For a baker yeast, temperature and time can be most important to control. In a relationship, it may be to accept each other for who you are that is the critical factor :-)
How can you identify critical factors?
Often, it is enough to use common sense. Other times it can be necessary to combine common sense with statistical tools. Six Sigma use Process mapping to visualize process steps and identify factors that affect the outcome of each process step. Statistical tools can determine how much the various factors contribute to the overall variation of quality. Graphical analysis, Components of Variation (CoV), multivariate analysis and experimental design (DOE) can be used for this purpose.
What is the acceptable level and variation of critical variables?
First of all you need a good measurement. Measuring System Evaluation can be used to determine measurement uncertainty, as described in this video:
Next, you need to understand how the critical factors affect the final result. What level and variation is acceptable for the critical factors?
To decide this you can analyze historical data or you can use correlation, CoV or DOE to investigate and quantify this relationship.
How can you control a critical factor?
Once you know the wanted level and acceptable variation of the critical variable, you can monitor it in a Control Chart, using SPC.
If you observe special cause variation in a Control Chart you should examine it and solve the cause.
If the average is drifting, you should investigate why and make the necessary adjustments.
If the normal variation is an issue, you need to reduce the variation. This can be more challenging. If humidity is a critical factor, it can be controlled by installing air conditioner. If the pH is critical, the allowed variation of pH may need to be reduced to reduce the normal variation.