Lesson 10 : Process capability An important part of any SPC implementation is the use of process capability indices. There are several capability indices Cp, Cpk, Ppk, Cpm, NCpk. In this lesson we explain the most common used indices Cp, Cpk, Pp and Ppk. There is some confusion about the use of these indices. In … Read more
Lesson 9: Attribute control charts with low average We are now going to look at a particular problem you can encounter with attribute control charts.We will generate four streams of data from a process and create a special cause of variation in each data stream. Now we will look at control charts for all four … Read more
Lesson 8: Scatter chart When we want to reduce or eliminate a problem, we will need to come up with ideas or theories about what is causing the problem. One way to check if a theory should be taken seriously is to use a scatter chart, also called regression analysis. To use a scatter chart, we first … Read more
Lesson 7: Pareto chart A Pareto chart helps us to identify priorities for tackling problems. The Pareto principle (named after a 19th century Italian economist) states that 80% of defects or problems usually arise from about 20% of the causes. Let’s look at data from an imaginary process. The columns in the table represent 10 … Read more
Lesson 6: Poisson and “X” control charts using attribute data In lesson 5 we created control charts for Binomial data. Binomial data is where we look at products or services, and for each, decide it as a “pass” or a “fail”. It is not always best to classify a whole product in this “all or … Read more
Lesson 5: Binomial control charts In lesson 2 we looked at Xbar and Range control charts. In lesson 4 the X (individual value) chart was introduced. In both these cases, we used variable or measurement data. This is data which comes from a continuous scale. There is a different type of data called “attribute” data. Attribute data … Read more
บทที่ 2: แผนภูมิควบคุมค่าเฉลี่ยและพิสัย (Xbar & Range Control Charts) In lesson 1 we discovered why we need control charts. Now we are going to learn how to draw the control charts. We use different types of control charts for different types of data. Data can be divided into two major categories, variables and attributes. ในบทที่ 1 … Read more
Lesson 1: ความผันแปรและแผนภูมิควบคุม (Variation and Control charts) One of the most important names in the history of statistical process control is Deming as explained above. Deming used a famous simulation to explain the principles of variation called: The red bead experiment. While explaining the principles of variation we like to honor Deming by using his … Read more
บทนำ : แนะนำ SPC และนิยามศัพท์ แนะนำการควบคุมกระบวนการด้วยหลักการทางสถิติ(Statistical Process Control : SPC) และเว็บไซต์นี้ แนะนำการควบคุมกระบวนการด้วยหลักการทางสถิติ(Statistical Process Control : SPC) และเว็บไซต์นี้ Introduction to Statistical Process Control (SPC) and this website แนะนำการควบคุมกระบวนการด้วยหลักการทางสถิติ(Statistical Process Control : SPC) และเว็บไซต์นี้ Statistical Process Control is a combination of techniques aimed at continually improving production processes so that the customer may depend on the uniformity … Read more