"The devil is in the details"
Improving quality is about understanding and controlling variation.
Several variables influence a result. However, some variables are more important than others.
Across industries and even in personal pursuits, the essence of quality often lies in managing the intricate details. From the meticulous training of an athlete to the precise baking times of a patisserie, mastering these nuances can lead to consistent excellence.
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.
Understanding Variation: The Six Sigma Way
One of the well-known methodologies emphasizing the significance of understanding variation is Six Sigma.
Through its statistical tools, Six Sigma provides insights into variations and pinpoints the variables that are paramount to quality.
By controlling the variation of critical variables you can achieve the wanted result.
What is a Critical Variable?
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 Variables?
Sometimes it is enough to use common sense. Other times it can be necessary to combine common sense with statistical tools.
Process mapping helps you visualize the process steps and identify variables that affect the outcome of each process step.
Statistical tools are pivotal in identifying the most influential variables. Techniques such as graphical analysis, regression analysis, Variance Components (or Components of Variance), ANOVA (Analysis of Variance), multivariate analysis, and experimental design (DOE) are all valuable in this regard.
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 variable affect the final result. What level and variation is acceptable for the critical variable?
The techniques already mentioned to identify critical variables can be used to understand the acceptable levels.
How can you control a critical variable?
To effectively control these variables, tools such as Statistical Process Control (SPC), prove invaluable. Once you know the wanted level and acceptable variation of the critical variable, you can monitor it in a Control Chart.
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.
