Lean Terms from the Continuous Improvement Companion
An andon light, in its most common use, is a status indicator for a work area. It generally has green, yellow, and red lights in a stack. As the operator experiences abnormal conditions, he or she lights a different color. The colors have meaning. Yellow might be a call for Read more…
Machines are essential to production environments, but not all machines are created equal. The impact of breakdowns varies widely. Because resources are limited, it is important to have a strategy to manage machines according to how critical they are to the operation and how hard they are to repair. An Read more…
An assignable cause is a type of variation in which a specific activity or event can be linked to inconsistency in a system. In effect, it is a special cause that has been identified. As a refresher, common cause variation is the natural fluctuation within a system. It comes from Read more…
ABC inventory is a method of grouping materials based on cost and usage to assign them different inventory management processes. Typically, the segmentation is done by calculating out the annual usage of the parts and labeling the top 70% of them (by total cost) as ‘A’ parts, the next 25% Read more…
Availability is exactly what it sounds like. It is a state of readiness to perform a task or operation. The term can be applied to a person, process, or piece of equipment. OEE and Availability The term availability is a component of OEE or overall equipment effectiveness. This is a Read more…
Attribution theory is the study of the psychology behind how people attribute causes to the way they behave and the resulting outcomes. There are two types of attribution. Internal: With internal attribution, the cause of the behavior is believed to be a function of the characteristics and personality traits of Read more…
An artisan process is one that relies on the skills of workers over strong processes. In the past, artisans were held in extremely high regard. This was primarily due, though, to the lack of a reasonable alternative to obtain high quality goods. Modern production processes and the sophistication of products, Read more…
The Analytic Hierarchy Process, or AHP, is a decision-making tool developed in the 1970’s by Thomas L. Saaty. Its key characteristics are that it breaks big decisions into smaller ones, and relies on direct, one-on-one comparisons to make judgments. Essentially, the analytic hierarchy process breaks criteria into progressively smaller criteria, Read more…
Analysis of variance, also known as ANOVA, is a sophisticated statistical modeling technique that looks at variation within and between two or more groups. This is a useful tool in Six Sigma because being able to recognize variation in results lets you zero in on the process that created that Read more…
The alternative hypothesis is the assumption that there is a statistically significant difference between two sets of data. This is essentially the opposite of the null hypothesis. The alternative hypothesis is accepted if the null hypothesis is rejected. What this might mean in practice is that there is a statistical Read more…
Alpha risk is, in statistical terms, the chance of rejecting the null hypothesis when it is, in fact, true. In other words, it is a false positive (i.e. a good part is identified as a defect). This risk is also known as a Type-I risk, or producer’s risk. See Also: Read more…
The acceptance number is the highest number of nonconforming items that can be found in a sample for a lot to still be considered acceptable. This number is determined by statistical analysis and is based on the required quality level, lot size, and sample size. The underlying premise of using Read more…