Lean Six Sigma Glossary
5S – an important Lean Six Sigma waste elimination method which contributes to continuous improvement. This methodology was developed in Japan and actively used by Toyota Motor Corporation. 5S is a method focused on effectively organizing a work space. Although the origins of the 5S methodology are in manufacturing, it can be applied in software development, information and other fields. This method is based on five pillars: Sort (Japanese: Seiri), Straighten or Set in Order (Japanese: Seiton), Shine (Japanese: Seiso), Standardize (Japanese: Seiketsu) and Sustain (Japanese: Shitsuke).
6M – are typical cause categories from Ishikawa diagram which typically include: Machines, Methods, Material, Manpower, Measurement and Mother Nature. One more category – “Management” is often added turning 6M into 7M,
AIAG – Automotive Industry Action Group is a not-for-profit association where professionals from a diverse group of stakeholders – including retailers, suppliers of all sizes, automakers, manufacturers, service providers, academia, and government – work collaboratively to streamline industry processes via global standards development and harmonized business practices.
Analysis of Variance (ANOVA) - is a collection of statistical models used to compare whether samples are drawn from populations that have the same or significantly different means.
ASQ – American Society for Quality among other certifications provides Lean Six Sigma certifications at yellow, green, and black belt levels.
Benchmarking – the process of comparing one's business processes and performance measures to leading organizations’ processes and measures. Benchmarking also helps identifying areas, systems, or processes for improvements.
Black Belts – lead Six Sigma projects and mentor Green and Yellow Belts. They dedicate 100% of their time to Lean Six Sigma projects. LSSBBs have expert understanding of statistics and other Six Sigma methods.
Central Limit Theorem (CLT) – according to the theorem regardless of the shape (normal and non-normal) of the distribution of a population, the distribution of the sample means has an approximate normal distribution with sufficiently large (normally 30) sample size.
Champions – lead Lean Six Sigma projects implementation in organizations. They enjoy senior management’s support in initiating, planning, implementing and sustaining Lean Six Sigma quality management system. Champions come from middle and senior executive level. They remove project roadblocks and ensure that resources are available for successful project implementation.
CLT – see Central Limit Theorem.
Control charts – are commonly used in the control phase of the Lean Six Sigma DMAIC methodology to determine whether a business processes are in a state of statistical control. The charts were pioneered by Walter Shewhart and represent one of the seven Basic Tools of quality. The utility of control charts is that they help Lean Six Sigma practitioners separate common and special causes of process variation.
Correlation coefficient – is a statistic which describes the strength of the relationship between two variables. The coefficient is dominated with “r” and varies between -1 and 1. Negative correlation indicates inverse correlation (when X variable increases, Y decreases and vice versa). Positive correlation indicates positive association of variables (when X variable increases, Y increases and vice versa). The strength of the correlation is higher when “r” is closer to -1 or 1 and decreases as “r” approaches 0. Correlation does not mean causation.
CSSBB – Six Sigma Black Belt Certification by ASQ
CSSGB – Six Sigma Green Belt Certification by ASQ
CSSYB – Six Sigma Yellow Belt Certification by ASQ
Defect – an instance or occurrence when a unit (product) does not conform to customer requirements.
Defective – a unit (product) which contains at least one defect. It is possible for a defective unit to contain multiple defects.
Defects per unit (DPU) –one of the process performance metrics which shows average number of defects per unit of product. Defects per unit (DPU)=number of defects / number of units.
DMAIC – a 5 phase methodology which is used for achieving Six Sigma business process quality. The acronym DMAIC stands for: Define, Measure, Analyze, Improve and Control.
DPMO – a commonly used Lean Six Sigma metric. The acronym stands for Defects per Million Opportunities. DPMO measures how many defects a process creates per million opportunities. Opportunity is an opportunity for a defect (not to confuse with defective). A process performing at Six Sigma level produces 3.4 defects per million opportunities in the short term. DPMO=DPO x 1,000,000.
DPO – a Lean Six Sigma Metric. DPO measures the likelihood of a defect occurring per opportunity. Opportunity is an opportunity for a defect (not to confuse with defective). DPO=Defects / (Units x Opportunities).
DPU – a commonly used Lean Six Sigma metric. The acronym stands for Defects per Unit. DPU measures average number of defects per unit. Defect is not the same as defective (e.g. a defective screwdriver can have multiple defects). DPU=Defects/Units. For example, if 7 out of 10 screwdrivers are defective and have 25 defects then DPU=25/10=2.5.
Executives – are members of top management. They allocate resources for Lean Six Sigma initiatives. Executives’ support is vital for successful implementation of Lean Six Sigma projects. They determine which Lean Six Sigma projects align with organizations’ culture and goals.
Failure Mode and Effects Analysis (FMEA) – a technique for evaluating risk of failure. Each mode is rated 1 to 10 on severity, probability of occurrence and detection. Three values are multiplied to produce Risk Priority Number (RPN).
Father of Six Sigma – Bill Smith, an engineer who worked for Motorola is often referred to as the “Father of Six Sigma”. In 80’s he approached then Motorola’s CEO Bob Galvin and suggested to focus on defects caused by manufacturing process variation. Bill Smith believed that achieving drastic decrease in defects was possible by eliminating variation. This would result in less waste, increased savings and customer satisfaction. In 1987, Galvin launched a long term quality program, called “The Six Sigma Quality Program”.
Green Belts – assist Black Belts and Master Black Belts in carrying out Lean Six Sigma projects. LSSGBs are involved in Lean Six Sigma projects on part-time basis. They have solid understanding of Lean Six Sigma principles and are trained in data collection and statistical analysis methods.
Histogram – a graph used to show frequency distributions i.e. how often different values in a given set occur. Histograms are “built” using vertical or horizontal bars whose lengths indicate quantities.
IASSC - International Association for Six Sigma Certification provides Lean Six Sigma certifications at yellow, green, and black belt levels.
ICBB – IASSC Certified Lean Six Sigma Black Belt
ICGB – IASSC Certified Lean Six Sigma Green Belt
ICYB – IASSC Certified Lean Six Sigma Yellow Belt
Juran Trilogy – see Quality trilogy.
Kaikaku – a term used in Lean Production describing drastic process improvement targeting waste elimination. Kaikaku is focused on implementing breakthrough changes unlike Kaizen which implies incremental continuous changes.
Kaizen – key concept in Lean Manufacturing and Lean Six Sigma implying Kaizen is a system of continuous improvement in quality. It is based on the assumption that incremental changes routinely applied and sustained over a long period lead to substantial improvements.
Kurtosis – measure of “peakedness” of a data distribution. Kurtosis quantifies whether the shape of the data distribution matches the Gaussian distribution. A negative kurtosis is associated with a flatter distribution. A positive kurtosis is associated with a more peaked distribution.
Lean Six Sigma – methodology which combines a set of techniques and tools for process improvement from Six Sigma and waste elimination from lean manufacturing.
Master Black Belts – act as trainers and Lean Six Sigma consultants in organizations. They normally coach Black Belts and Green Belts. LSSMBBs develop, define and implement complex Six Sigma projects. They also work with Champions and Leaders to create commitment to projects and remove roadblocks. It is the highest rank within Lean Six Sigma quality management system.
Mean – a measure of central tendency commonly used in lean six sigma projects. It is found by calculating the sum of the given data set, and then dividing the sum by the total number of values in the set. The mean of the following data set is calculated as follows: 2,2,5,8,9 is (2+2+5+8+9)/5=5.2. Mean is also referred as average.
Median - the middle value in a sorted data sample, a population, or a probability. The median is found by sorting all the values from lowest value to highest value and picking the middle one (e.g. the median of 2, 2, 7, 8, 12 is 7). With even number of observations there is no single middle value. The median is usually defined to be the average of the two middle values.
Mode – a measure of central tendency which represents the number occurring most frequently in a given set of numbers. The mode of the following set of numbers: 1,1,3,4,5,8,8,8,9,9 is 8.There might be more than one mode in a set of numbers.
Muda – a Japanese word for “waste” and a key concept in Lean Six Sigma philosophy. There are 7 variations of muda which consume resources, but do not add value: overproduction, waiting, transporting, processing, inventory, motion and correction.
NIST – National Institute of Standards and Technology is the federal technology agency that works with industry to develop and apply technology, measurements, and standards.
Process mapping – graphical representation of a process flow detailing process start, end, steps, decision points etc. Flowcharts are often used to map various processes for Lean Six Sigma projects.
Process Owners – staff member responsible for a business process which is being improved by a Lean Six Sigma project. Process Owners may not be involved in Lean Six Sigma projects on a daily basis, but they provide valued input in defining process specifications and validating final results.
Quality Trilogy – a model of quality improvement first described by Juran. This model, which is also called Juran Trilogy, consists of three processes necessary for managing quality: quality planning (provides a system that is capable of meeting quality standards), quality control (used to determine when corrective action is required) and quality improvement (creating breakthroughs to unprecedented levels of performance).
Return on Investment (ROI) – commonly used Lean Six Sigma financial measure which is used to evaluate the efficiency of a Six Sigma project or to compare the efficiency of a number of different projects. To calculate ROI, the income (e.g. financial gains, dollars saved or costs avoided) from a project is divided by the cost and is expressed as a percentage or a ratio: ROI=Income/Cost x 100%.
Scatterplot – also referred as scatter diagram, scattergram, scatter diagram or scattergrapgh, illustrates the relationship between two variables on X and Y axis. Data are plotted as dots on the graph. Each dot’s position is dependent on pairing a value of the variable on the X axis with a value of the variable on the Y axis. If dots fall along a line pointing north-east (positive correlation) or south-east (negative correlation) then variables are correlated. The closer the dots are clustered around the line i.e. more they resemble a line, the stronger correlation is. Scatterplots depict correlation, but not causation.
Seiketsu – one of the 5S pillars implying creation of a standard approach to maintain high standards of housekeeping and work space organization. In this phase sorting, straightening and shining duties are assigned to regular job responsibilities. Seiketsu can be translated in English as “standardize”.
Seiri – one of the 5S pillars implying sorting through everything in each work area and removing materials, tools, supplies and equipment which are not frequently used. Also using red tags to label the means of production which are not frequently used and placing them in a separate storage. Seiri can be translated in English as “sort”.
Seiso – one of the 5S pillars implying maintaining a work space neat and safe. Shining prevents machinery and equipment from deterioration. Working in a clean work space increases probability of noticing malfunctions in equipment machinery, such as leaks, vibrations, and breakages. Seiso can be translated in English as “shine”.
Seiton – one of the 5S pillars implying arranging all necessary means of production (tools, materials etc.) in order, so they can easily accessed as needed in a production process. Seiton can be translatde in English as “straighten” or “set in order”.
Seven Basic Tools of Quality – identified by Kaoru Ishikawa, these are seven graphical tools used for quality control and management. The seven basic tools of quality include: fishbone diagram, check sheet, control charts, histogram, Pareto chart, scatter diagram and stratification.
Shewhart charts – see Control charts.
Shitsuke – one of the 5S pillars implying institutionalizing good practices and maintaining correct procedures. This phase is crucial for ensuring continuity of waste elimination efforts. Ultimate goal is to standardize effective production processes, so over time workforce develops and maintains effective work habits. Shitsuke can be translated in English as “sustain”.
Skewness – a measure of the asymmetry of a distribution. A distribution with a longer tail to the right has a positive skew. A distribution with a longer tail to the left has a negative skew.
White Belts – part-time Lean Six Sigma project participants. LSSWBs have basic understanding of Lean Six Sigma principles and methodology.
Yellow Belts – assist Green Belts and Black Belts carrying out Lean Six Sigma projects. LSSYBs may be involved with the project tasks which do not require in-depth knowledge of Lean Six Sigma methodology but are still important for an overall success.