When we are trying to determine the relationship between two variables, one of the relationships might be the equation of a straight line [i.e., y = (f)x.] With the least squares method, the team is using the linear equation. The linear equation represents the points found on the scatter diagram. In essence, the team is using the least squares criterion, meaning that the line fitted to the paired data points must be such that the sum of the squares of the vertical distances from the points to the line is as small as possible.

Levene’s test is used to access variation homogeneity. Levern’s test is useful for parametric tests such as the T-test and Analysis of Variance (ANOVA) that require a precondition of homogeneity.

Pioneered by the lean guru Taiichi Ohno, referred to load leveling as “heijunka” (HIGH JUNK AH), meaning a technique for reducing the mode of (waste). Load leveling is a method for reducing large fluctuations in customer demand.

Lean guru Taiichi Ohno can be quoted, “The slower, but consistent tortoise causes less waste and is much more desirable than the speedy hare that races ahead and then stops occasionally to doze. The Toyota Production System can be realized only when all the workers become tortoises.” You could have leveling by volume, or leveling by product. Leveling by volume: A family of products goes through essentially the same process steps.

Dr. Genichi Taguchi, a Japanese quality consultant and engineer, came to the United States in the 1980s concentrates on loss. In conjunction with this view of quality, he developed the idea of a loss function. If we think of quality in a competitive way, we should view that there is a target value (i.e., nominal-is-best, larger-is-best, or smaller-is-best). When measuring an end-product-parameter, any departure away from the designer’s intended target creates a loss to society, or a loss to the producer. Either way, ultimately the customer ends up paying for it.

A defect location check sheet (also known as a defect map or a measles chart) is a structured, prepared form for collecting and analyzing data that provides a visual image of the item being evaluated so that data can be collected visually rather than merely collecting a count of the number of defects.

A matrix diagram is a tool that illustrates the critical relationships between or among two or more groups. It can be enhanced to show things like the strength of the relationship or the different aspects of the relationship.

Measurement error is the difference between the actual value of a characteristic being measured and the value obtained by the measurement system. Given that the measurement device is discriminate (sensitive to variation of the product being measured), with each repeat of a measurement, there will be variation. By the way, if no variation is seen, measure with a more discriminate device. There is systemic error and random error. The systemic error occurs when we use the measurement device in the same way and in the same condition. The random error will vary from reading to reading. There can also be variation due to the human element (when applicable).

The nominal scale is a measurement scale that lists names (categories.) Nominal data is discrete data and there is no particular order with a nominal measurement scale.
Think of going to your favorite fast food restaurant. For example, the restaurant manager might list the first names of the employees, or might list the models of the cars that they drive. These are examples of a nominal measurement scale. You could put the names in alphabetical order, but the names really have no meaning of the rank order. When you think of nominal, think of the word ‘name’ – both start with an ‘N.’

The nominal group technique (NGT) is a decision-making method used by teams to separate the vital few from the trivial many.

Separation of the important items from the not-as-important items can be made using various techniques. One technique is majority rule. The decision made by majority rule is quick, but those in the minority feel alienated because they lose. It is better to get a win-win decision. A popular nominal group technique is to give everyone on the team five votes. Some use Post-it notes where one note equals one vote. Each member can vote on one item and use all of their five votes on that one idea. The team member may choose to split his or her votes among a few different ideas. For example, they might want to put three votes on one idea and two votes on another idea. They might even want to put one vote on each of the five items.

The reality in the world is that variation exists. If variation did not exist, if we made a product right the first time, every product would be right the first time. The same would hold for providing a service. But, the reality is that we live in a world where variation does exist and therefore every now and then we will have to deal with a defect, mistake, flaw, or error. Another reality is the variation can be random, meaning that no undue influence is coming from the people, the machinery, the materials, the methods, the measurements, or from the environment. If the variation in a process is random, it is at a state of normality. Other names for normality include common-cause, chance variation, and random variation.