Statistically Based Quality Improvement for Variables.

Summary: Chapter 11 – Statistically Based Quality Improvement for Variables
This chapter starts with a friendly tone as it seeks to usher in everyone who may fear the field of statistics. The main goal or focus of the chapter is on the use of statistical tools as the foundation for continual improvement. Different techniques are presented as well as different charts. As indicated, while learning about these techniques and charts is important, it is also crucial to learn the application process of the same.
The first encounter with statistical concepts begins with the term statistical thinking which is explained as the ability to draw conclusions based on data. Often, people make decisions based on their feelings or intuition and this is outlined as wrong because it yields biased conclusions or opinions. So, it is crucial to consider statistical thinking in this day and age. This kind of thinking is based on three concepts which are as outlined below:
* All work occurs in a system of interconnected processes.
* All processes have variation.
* Understanding variation and reducing variation are important keys to success.
The adoption of statistical tools continues to happen all over the world. Firms have taken up the use of statistical tools to help gain a competitive advantage over their competitors. However, as many have learned, it is not always successful and patience is quite crucial. Well, several reasons may contribute to the failure of statistics in the workplace. Some of these reasons include the lack of knowledge about the tools, disdain over all things mathematics, cultural barriers, communication barriers between statistical specialists and managers, lack of practical application knowledge on statistics, poor understanding of the scientific method, etc.
Understanding Process Variation
Understanding variation is key to the end result. There are two types of process variation that commonly occur. There is the random variation which cannot be controlled hence the name uncontrolled variation and then there is the nonrandom variation which has an identifiable cause. The random variation is centered on a mean and occurs with a somewhat consistent amount of dispersion while the nonrandom variation results from some event. Here are diagrams to showcase the two.
Random
Nonrandom
Still on variation, there is a term known as process stability. This term simply means that the variation under observation is random variation. Process charts are used to help determine process stability. They are graphs that are designed to signal process workers when a nonrandom variation is occurring in a process. To ensure the stability of processes, data has to be gathered in samples. Several sampling styles or techniques can be used. There are random samples which gift an equal chance of selection to all products. There is the systematic sampling method which means that samples can be systematic eith...