Freedom from physical or psychological harm, stress or injury.

Safety Stock

A level of stock that is maintained buffer against stock outages due to counter uncertainties in demand and variation in quality and downtime.

Sales, Inventory & Operations Planning

A structured and collaborative planning process between sales, finance, procurement, manufacturing and logistics, with the purpose of arriving at consensus on how to best avoid lost sales, utilize assets, and maintain high levels of service.

Sales & Operations Planning


One or more observations drawn from a larger collection of observations.


In statistics, quality assurance, and surveys, sampling is the selection of a subset of individuals from within a statistical population to estimate characteristics of the whole population. In industrial engineering and time analysis, sampling is the periodic observation of every X repetition of a process over days or weeks to gain a representative set of data.

Sampling Bias

In statistics, sampling bias is the collection of data such that some members of the population have a lower or higher sampling probability than others.

Scatter Diagram

Scatter Plot

A graph in which the values of two variables are plotted along two axes to create patterns of points which revealing any correlations.

Scientific Method

The systematic observation, measurement, experimentation, formulation, testing, and modification of hypotheses. A method of pursuit of knowledge and understanding followed in the natural sciences since the 17th century.


The defined boundary of a project, an agreement, a set of responsibility and so forth. The scope defines what is covered and what is not.


A framework used in Agile for developing, delivering, and sustaining complex products, in which small teams of ten or fewer people break their work into goals that can be completed within iterations known as sprints into timeboxes of two to four weeks. The Scrum Team track progress in 15-minute time-boxed daily meetings, called daily scrums or huddles. Teams hold sprint reviews to demonstrate the work done, and sprint retrospective to continuously improve their process, at the end of each sprint.

Scrum Poker

Scrum of Scrums

A method to scale Scrum up to large groups. This involves dividing the larger group into teams of five to ten people. Each daily scrum within this sub-team ends by designating one person as the ambassador to participate in a daily meeting with other teams' ambassadors. This daily meeting is called the Scrum of Scrums.

See also Scrum


Abbreviation for Standardize, Do, Check, Act. An variation of the plan-do-check-act cycle of continuous improvement. It is used when it is necessary to first stabilize a process by establishing basic standards, following those standards, checking their effectiveness, and making adjustments.


Japanese for "organizing".

See Sort


Japanese for "cleaning".

See Sweep


Japanese for "sanitary".

See Sanitize


Japanese for "proper arrangement".

See Straighten

Self-directed Teams

Self-directed Work Teams


A master teacher of a specific area of expertise. In the context of Lean and Six Sigma, the sensei is someone who has mastered their field as a result of years of practical experience in transforming organizations. Sensei is the Japanese word for “teacher.”

Sequencial Changeover

When changeover can be completed within takt time, it is possible to perform them in series across processes in a flow line. Sequential changeover allows the time lost due to changeover to be limited to one takt. In a sequential changeover method, a set-up team or changeover specialist follows the operator and goes from process to process. By the time the operator has completed one cycle of their work within takt time, the process has been changed over to the next product.

Sequencial Set-up

Sequential Pull System

A pull system when it is impractical to hold inventory of each part in a supermarket due to a high number of part numbers. The signal to produce is a build-to-order but the inventory in the system is strictly limited and the sequence is maintained by FIFO.

See also First In, First Out

Set-based Concurrent Engineering

A product design approach in which developers evaluate sets of design ideas rather than a single on. This involves a set of practices, including:

  1. Using trade-off curves and design guidelines to characterize the known feasible design sets, thereby focusing the search for designs.
  2. Identifying and developing multiple alternatives, eliminating alternatives only when proven inferior or infeasible.
  3. Starting with design targets, allowing the actual specifications and tolerances to emerge through analysis and testing.
  4. Delaying the selection of the final design or establishment of the final specifications until the team knows enough to make a good decision.

The benefits of this approach include organizational learning, as well as reduced time and costs to develop product by avoiding false starts and rework due to committing to an design idea too early.

Set in Order

Set Parts System

A material replenishment system used at Toyota assembly factories to deliver the correct set or kits of parts to the point of use at mixed model lines.

Setup Reduction

The process of reducing the amount of time to setup or changeover a process from the last part for one product to the first good part for the next product.

Setup Time

Seven Wastes

Shadow Board

A visual methods of storing tools or materials at or near the point of use while indicating any items that are in use or missing. A shadow board is made of outlines or “shadows” painted on board in the shape of individual items. This makes it obvious where each item be put away and also reveals any items that are missing at the end of the work cycle, shift or day.


See Sweep


Japanese for "discipline".

See Self-discipline


The creation of flexible manpower lines or processes that can be operated with multiple people or just one person as demand changes. Shojinka is Japanese word for "manpower minimization".

See also Staffing Linearity



The Greek letter s (sigma) refers to the standard deviation of a population.

See also Standard Deviations


Single minute exchange of dies

Abbreviated as SMED, a system of set-up reduction and quick changeover pioneered and developed by Shigeo Shingo.

SIPOC Diagram

A tool used to visualize the Suppliers, Inputs, Processes, Outputs and Customers for a series of processes. SIPOCS identify all relevant elements of a process at a high level as well as possible stakeholders. Improvement teams use SIPOC diagrams at the earliest stages of project planning to determine what is in and out of scope.

Six Sigma

The Greek letter ‘σ’ (sigma) is used as the symbol for standard deviation. Six sigma refers to six standard deviations within the output of a process.

As a measure of process capability, process that is at six sigma creates no more than 3.4 defects per million opportunities. A process is at six sigma when the amount of process shifts and drifts are controlled over the long term to within +1.5 standard deviations from the centered mean.

As an improvement method, Six Sigma follows the DMAIC approach to solve problems by applying sophisticated statistical analysis.

Six Thinking Hats

A framework to support decision-making, problem-solving, creative thinking or other mental efforts by using a combination of thinking styles. The six thinking hats each represent a thinking style and are assigned its own color. The six hats are:

  1. Blue, for big picture thinking, thinking about the process
  2. White, for rational, fact-based, data-driven thinking
  3. WHITE "Facts & Information" Information
  4. Red, for feelings, passion and emotional thinking
  5. Black, for critical, pessimistic or negative thinking
  6. Yellow, for hopeful, optimistic, positive thinking
  7. Green, for innovate, open-minded, creative thinking

Each person may have one or more preferred thinking styles. In practice, the Six Thinking Hats approach encourages people to "try on" different colors of hats to see the issue new new ways.

Introduced by Edward de Bono in Six Thinking Hats (1985).

See also Lateral Thinking

Skill Matrix

This chart shows at a glance how much cross-training you have in your organization between different people and different tasks. Also called a versatility matrix, or versatility chart.

Small Group Activity

Structured problem-solving and improvement activities by team members in the workplace. Small groups learn tools and methods to identify and address root causes of problems they encounter in their work. The Small Group Activity format empowers people to improve their own work, builds ownership of the process, improves communication and builds problem-solving skills.


An acronym for setting goals that are:

  • Specific
  • Measurable
  • Attainable
  • Relevant
  • Timebound

Soft Savings

The intangible benefits of improvement that are difficult to associate directly with expense line items. Some soft savings may relate to human factors such as improved morale, job satisfaction employee engagement, trust and communication, which can indirectly improve productivity, quality and cost. Soft savings can be more tangible, such as faster lead-times, saved space, or improved cleanliness, which can contribute to savings if those benefits are used to increase revenues or reduce expenses.

Contrast with Hard Savings


Key points reviewed at the start of a meeting or workshop to improve team meeting efficiency and effectiveness. Safety, Purpose, Agenda, Conduct, Expectations, and Roles & Responsibilities.

Spaghetti Diagram

A sketch showing the actual movement of people or product through a series of process steps. A process analysis tool used to highlight excessive walking, searching, transportation, and poor workplace layout. The diagram often resembles a tangled plate of spaghetti.

Span of Control

The scope of work responsibilities of a leader, including the number of team members and subordinates who the leader supports.

Spiral Up Jidoka

The idea within the Production Preparation Process of taking autonomation one step at a time rather than in one leap, to ensure that the automation was as simple, appropriate and as low cost as possible. There are many catalog solutions for going from step 1 to 4 that do not support Lean manufacturing. The spiral up steps are usually written as:

5. Automatic unloading

4. Automatic return to home position

3. Automatic stop

2. Automatic feed

1. Automatic processing

These are counted from bottom to the top because it is a spiral upwards.

See also Production Preparation Process

See also Jidoka

Sporadic Loss

Process failures or deviations from normal operations that are sudden and significant.


A short, fixed interval of time during which an agile team commits to and delivers a piece of value to the customer. The unit of iteration in a scrum.

Sprint Planning

An event in scrum that kicks off a sprint. The purpose of sprint planning is to define what can be delivered in the sprint and how to accomplish the work. The whole scrum team collaborates during sprint planning.

Sprint Retrospectives

Special Cause Variation

A shift in output caused by a specific factor such as process input parameters or environmental conditions. Special causes can be accounted for directly and potentially removed as a source of variation. Special cause variation is a measure of process control.


The key performance indicators Safety, Quality, Delivery, Cost. The order of SQDC is based on the belief that processes that are safe and capable of delivering quality on-time result in low costs. This is in contrast to a over-emphasis on cost cuts that can lead to safety incidents, poor quality, late deliveries.

Staffing Linearity

The ability to easily rebalance the staffing of a connected series of processes such as an assembly line as the demand fluctuates up or down.


The people who have a vested interest in the outcome of a process, project or change. Stakeholders include, but are not limited to, the people who are directly involved in the work. Stakeholders may or may not bear the cost of the change, may or may not benefit, and may or may not have influence on the outcome. Stakeholders may be internal or external to the organization, such as team members working in the process, upstream processes,downstream processes, support function staff, the leadership team, internal customers, external customers, vendors and suppliers, shareholders, financiers and creditors, regulatory agencies, local government, community members and so forth.

Stakeholder Analysis

The process of identifying stakeholders in the early stages of a project or proposed change. Stakeholders are grouped by their levels of engagement, interest, and influence in the outcome of the project or change. The output of a stakeholder analysis is a communication plan addressing how to reach each stakeholder group, remove potential obstacles and enlist them as supporters.

Standard Deviations

Also called sigma (σ), this is a measure in statistics of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean of the set. A high standard deviation indicates that the values are spread out over a wider range. Standard deviations are used as a scaling factor to convert upper and lower specification limits to Z. Therefore, a process with three standard deviations between its mean and a spec limit would have a Z value of 3 and commonly would be referred to as a 3 sigma process. Standard deviations are also used to measure confidence in statistical conclusions drawn from the results of experiments.

Stand-Up Meeting

A brief meeting by members of a natural work team or project team to communicate status, review priorities and identify issues. Typically held at the start of early in the work day, at a visual display board in the place of work.

See also Huddle

Standard In-Process Stock

Stand In the Circle

The act of standing still in one location to observe and deeply understand a process. Named after the practice of Taiichi Ohno who would carry a piece of chalk and draw a circle around young managers and engineers who did not see the waste or unsafe processes in the areas for which they were responsible. They were required to stand in the circle and observe until they understood what they had to do.

Standard Operating Procedure

Abbreviated SOP, it is a set of step-by-step instructions to help people carry out their tasks in a consistent, safe, efficient and consistent way.

Standard Work

The most efficient combination of labor, equipment, and material. The three elements of standard work are:

  1. takt time,
  2. work sequence
  3. standard work-in-process

Performing standard work allows for a clear and visible "normal" or operation in good condition. Any deviation from standard work indicates an abnormality, which is then an opportunity for improvement.

Standard Work Combination Sheet

A time graph detailing the sequence of production steps assigned to a single worker performing Standard Work. This document outlines the best combination of worker and machine times.

Standard Work Combination Table

Standard Work Sheet

A document showing a top-down view of the work area layout, equipment, work sequence, staffing, standard WIP, raw materials and finished goods, and safety and quality checkpoints. Used as a visual management tool.

Standard WIP

Standard Work-in-Process

The minimum work-in-process inventory needed to maintain standard work. Standard WIP includes:

  1. items completed in a machine at the end of an automatic cycle
  2. items within processes that have cycle times exceeding Takt time
  3. items currently being worked on or handled by the operators performing standard work

Abbreviated SWIP. Also called standard in-process stock.


The act of establishing specific conditions, processes, or practices that meet requirements set by customers, regulators or the company. Standardization provides a stable basis from which to make changes and test the results following a PDCA cycle. The results from changes made without standardization are unreliable because underlying conditions may not be stable and repeatable.

Standardized Work

Standardized Work Combination Table


Expectations, rules, principles or documented requirements that sets a minimum acceptable level of behavior and/or outcomes.

Statistical Process Control

Abbreviated SPC, it is an approach to quality control which uses statistical methods to monitor and control a process.


The 2nd of the 5S activities which involves properly arranging all necessary items for easy access. The goal can be expressed as "to have a place for everything, and have everything in its place."


The sorting of data into distinct groups or layers based on one or more categories such as location, timing, income level, age and so forth.


An individual or group exercise to review activities to be stopped, started or continued based on whether they contribute toward an objective.

Stop-the-Line Authority

When workers are able stop the line to indicate a problem, this is stop-the-line authority. The production line or machine remains stopped until the supervisor, manager, engineer, maintenance personnel, support staff or president have identified the problem and taken corrective action.

Suggestion System

A system for encouraging workers to identify wastes, safety, and environmental concerns and submit improvement ideas formally. Rewards are given for suggestions resulting in cost savings. These rewards are typically shared among the production line or by the kaizen team.

Sunk Costs

Any expenditure that has already taken place and can not be undone. Decisions should not be made based on sunk costs.


The supermarket is a tool of the pull system to help signal demand for the product. In a supermarket, a fixed amount of raw material, work in process, or finished product is kept as a buffer to schedule variability or process reliability. A supermarket is typically located at the end of a production line.

Supermarket Pull System

A pull system in which there is a supermarket, or a storage area holding an specified amount of each product it produces. As material is withdrawn from the supermarket by the downstream process, a kanban or other type of signal is sent upstream to the producing process.

Sustainable pace

An appropriately energetic rate of speed for a team to do its works so that it delivers good value consistently over an extended period of time without burning out.

Swim Lane Maps

Process flow diagrams that visualize the functional responsibilities for the sub-processes and steps of a business process using horizontal rows. These rows resemble lanes in a swimming pool. Swim Lane Maps are used to visualize complex, cross-functional process flows and highlight problems that can occur in communication, information transfer and handoffs, or unclear requirements.

Swim Lane Mapping

The activity of creating Swim Lane Maps for the purpose of understanding and improving process flows.

SWOT Analysis

A strategy development tool that puts an organization’s strengths, weaknesses, opportunities and threats on a two-by-two matrix.

System of Profound Knowledge

A requirement identified by Dr. W. Edwards Deming for managers to successfully lead transformations. There are four elements to the System of Profound Knowledge

  1. Appreciation of a system, which includes understanding the end-to-end process involving suppliers, producers, and customers of goods and services
  2. Knowledge of variation, which includes the range and causes of variation in quality, and use of statistical methods
  3. Theory of knowledge, which includes concepts explaining knowledge, how it is acquired and the limits of what can be known
  4. Knowledge of psychology, including concepts of human nature and behavior

Systems Thinking

An approach to solving problems or creating innovations which examines the overall system and the complex interactions of its components rather than focusing on the components separately.