Lean lexicon

  • Activity-Based Costing (ABC)
    An accounting technique that enables an organization to determine the actual cost of a product or service by tracing the cost back to the specific activities that produce or provide it. Com­pare to Traditional Cost Accounting (TCA).
  • Symmetry
    When opposite sides of a part, tool, ma­terial, or fixture are different in size, shape, or relative position. Asymmetrical differences can be hard to spot, resulting in errors. Compare to symmetry.
  • Autonomous maintenance
    A program in which equip­ment operators share responsibility with maintenance staff for the care of the equipment they use.
  • Batch delay
    The amount of time a service operation or product unit waits while other operations or units in the lot, or batch, are completed or processed.
  • Batch processing
    The movement of products through the manufacturing process in large numbers of identi­cal units at once. Entire batches, or lots, are sent to each operation in the production process at the same time. Also known as large-lot processing. Compare to one-piece flow.
  • BTS
    (build to schedule) A metric that measures the per­centage of units scheduled for production on a given day that are actually produced on the correct day, in the correct mix, and in the correct sequence.
  • Capacity
    The ability of a machine and its operator to com­plete the work required.
  • constant order-cycle system
    An inventory-control system that features a fixed reorder date and a varying order quantity.
  • constant order-quantity system
    An inventory-control system that features a fixed order quantity and a varying reorder date.
  • constraining operation
    The manufacturing step that determines the upper limit on the number of finished parts that can be produced within a value stream. Also known as a bottleneck operation.
  • Constraint operation
    An operation that is long in dura­tion or is critical to completing a manufacturing process.
  • Contact method
    An error-proofing method that involves inspecting the size, shape, or color of an object to determine if any deviations exist.
  • Core processes
    The essential activities an organization must perform to produce products, complete order-fulfillment functions, maintain its assets, and complete all supporting business functions.
  • Cost shifting
    Moving costs from one account to anoth­er without creating any real savings. Cost shifting often hides waste rather than removing it.
  • Customer value
    An aspect of a product or service for which a customer is willing to pay.
  • Cycle time
    The time it takes to successfully complete the tasks required for a work process.
  • Defect
    A part, product, or service that does not conform to specifications or a customer’s expectations. Defects are caused by errors.
  • demand-supply chain
    All the parts, materials, and services supplied by outside sources that are necessary to produce a product or service.
  • DTD (dock-to-dock)
    A metric that measures how long it takes raw materials or sub-components coming into a plant to be turned into finished products.
  • End-of-the-line inspection
    An inspection or check done at the end of a process. See also judgment inspection.
  • Enterprise resource planning (ERP)
    The integration of all an organization’s departments and functions onto a single computer system that can serve all those different departments’ needs.
  • Error
    Any deviation from a specified manufacturing or business process. Errors cause defects in products or services.
  • Error-proofing devices
    Mechanical, electrical, or pneumatic devices that signal existing errors or prevent potential ones.
  • External processes
    Activities that an equipment operator can perform while the production line is still running. Compare to internal processes.
  • FIFO (first-in, first-out)
    A production method in which the oldest remaining items in a batch are the first to move forward in the production process.
  • 5S’s (Sort, Shine, Set in Order, Standardize, and Sustain)
    A method of creating a clean and orderly workplace that exposes waste and errors.
  • fixed costs
    Costs that aren’t changed by production or service/sales levels, such as rent, property tax, insurance, and interest expenses. They are the costs of being in business. Compare to variable costs.
  • fixed-value method
    An error-proofing method that ensures the right quantity of parts is used or the right number of activities are performed.
  • FTT (first time through)
    A metric that measures the percentage of units or aspects of a service that are completed without error the first time they go through your work processes.
  • Hard-cost savings
    Money that actually produces cash savings or profit increases and directly affects a company’s profit-and-loss statement. Compare to soft-cost savings.
  • Informative inspections
    An error-proofing method that provides timely information about a defect so that a root-cause analysis can be performed and process adjustments can be made before significant numbers of defects are created.
  • Internal processes
    Activities that an equipment op­erator must perform while the production line is idle. Compare to external processes.
  • Inventory
    Any part or product that is not immediately required for a customer order, such as excess raw materials, work in progress (WIP), and finished goods.
  • ITO (inventory turnover rate)
    A metric that meas­ures how quickly your company sells the products you produce.
  • Judgment inspection
    An error-proofing method in which a quality inspector or operator compares the final product or part with a standard. It is a type of end­of-the-line inspection.
  • Just-in-time inventory (JIT)
    A method of inventory management in which small shipments of stock are delivered as soon as they are needed. JIT minimizes stocking levels.
  • Kanban system
    A production-control system that uses cards or tickets as visual signals to trigger or control the flow of materials or parts during the manu­facturing process.
  • Kaizen
    Refers to activities that continuously improve all functions and involve all employees from the CEO to the assembly line workers. Kaizen aims to eliminate waste by improving standardized activities and processes.
  • Lead time
    The time it takes to complete an activity from start to finish; it includes batch and process delays.
  • Lean metrics
    Financial, behavioral, and core-process measurements that help you monitor your organi­zation’s progress toward achieving the goals of your lean initiative.
  • Load balancing
    Finding a balance between the volume of work that your organization needs to do and your capacity.
  • Load leveling
    Adjusting a production schedule to meet unexpected changes in customer demand.
  • Location indicators
    Markers that show where and how much material should be kept in a specific location in a work area.
  • Marketplace
    An area where materials are stocked in a supermarket system.
  • Motion-step method
    An error-proofing method that involves checking to make sure actions are performed in the correct sequence.
  • OEE (overall equipment effectiveness)
    A metric that measures the availability, performance efficiency, and quality rate of your equipment.
  • OFLT (order-fulfillment lead time)
    The average time that elapses between your company’s receipt of an order from a customer and when you send an invoice to your customer for the finished product or service.
  • one-piece flow
    The movement of products through the manufacturing process one unit at a time. Compare to batch processing.
  • OTD (on-time delivery)
    A metric that measures the percentage of units you produce that meet your customers’ deadlines.
  • Llanned maintenance
    Maintenance activities that are performed on a set schedule. Compare to reactive main­tenance.
  • PQ analysis table
    A tool that helps employees understand the types of products your organization produces and the volume that your customers demand. (The P in PQ stands for products; the Q stands for quantity of production output.)
  • Process
    A series of steps or actions that produces a completed order or product.
  • Process capacity table
    A tool for gathering informa­tion about the sequence of operations that make up a work process and the time required to complete each operation.
  • Process delay
    The time that batches or lots must wait until the next process begins.
  • Process route table
    A tool that shows the machines and equipment that are needed for processing a component or completing an assembly process. Aids in grouping your manufacturing tasks into work cells.
  • Production smoothing
    Synchronizing the production of your company’s different products to match your customer demand.
  • Productivity
    The ratio of output to input. It provides information about the efficiency of your core processes.
  • Pull system
    A production system in which goods are built only when requested by a downstream process. A customer’s order “pulls” a product from the production system. Nothing is produced until it is needed or wanted downstream. Compare to push system.
  • Push system
    A production system in which goods are produced and handed off to a downstream process,where they are stored until needed. This type of system creates excess inventory. Compare to pull system.
  • Quality function deployment
    A structured process that provides a means to identify and carry customer requirements through each stage of product and service development and implementation. Quality responsibil­ities are effectively deployed to anyneeded activitywithin acompany to ensure that appropriate quality is achieved.
  • Quick changeover
    A method of analyzing your organization’s manufacturing processes and then reducing the materials, skilled resources, and time needed for equipment setup, including the exchange of tools and dies. It allows your organization to implement small-batch production or one-piece flow in a cost-effective manner.
  • Reactive maintenance
    Maintenance activities that are performed after a piece of equipment breaks. Compare to planned maintenance.
  • Red-flag condition
    A situation in which the probability that errors will happen is high.
  • Return on investment (ROI)
    Profit from an investment as a percentage of the amount invested.
  • Root-cause analysis
    A process of identifying problems in an organization, finding their causes, and creating the best solutions to keep them from happening again.
  • RTY (rolled throughput yield)
    A metric that measures the probability that a process will be completed without a defect occurring.
  • Self-inspection
    An inspection performed by the opera-tor at his or her own workstation or area.
  • Shadow board
    A visual control technique that uses an image of an object to show where it should be stored.
  • Soft-cost savings
    Assets that are freed up so they can be used for another purpose. This contributes no positive change to a company’s profit-and-loss statement. Compare to hard-cost savings.
  • Source inspection
    An inspection that detects errors in the manufacturing process before a defect occurs in the final part or product.
  • Standard operating procedures (SOPs)
    Reliable in­structions that describe the correct and most effective way to get a work process done.
  • Standard operations
    The most efficient work com­bination that an organization can put together.
  • Standard operations combination chart
    A tool that enables you to study the work sequence for all your organization’s work processes.
  • Statistical process control (SPC)
    The use of mathematics and statistical measurements to solve an organization’s problems and build quality into its products and services.
  • Streamline
    To reduce the time spent in non-value­added steps, such as downtime, travel time, and inspecting or reworking materials.
  • Successive inspection
    An inspection that is performed after one operation in the production process is com­pleted, by employees who perform the next operation in the process.
  • Supermarket system
    A stocking system in which materials are stored by the operation that produces them until they are retrieved by the operation that needs them. When a store is full, production stops.
  • Symmetry
  • When opposite sides of a part, tool, material, or fixture are, or seem to be, identical. The identical sides of a symmetrical object can be confused during an operation, resulting in errors. Compare to asymmetry.
  • Takt time
    The total available work time per day (or shift) divided by customer-demand requirements per day (or shift). Takt time sets the pace of production to match the rate of customer demand. For example, if your customers demand 480 spark plugs per day and your production line operates 960 minutes per day, takt time is two minutes; if customers want two new contracts written per month, takt time is two weeks
  • Traditional Cost Accounting (TCA)
    An accounting technique that arbitrarily allocates overhead to the products or services an organization creates. It is unable to calculate the actual cost of a product or service. Compare to Activity-Based Costing (ABC). An accounting technique that arbitrarily allocates overhead to the products or services an organization creates. It is unable to calculate the actual cost of a product or service. Compare to Activity-Based Costing (ABC).
  • Value-added activities
    Tasks performed during the production of a product or service that increase its value to the customer.
  • Value stream
    All the activities that a company must do to design, order, produce, and deliver its products or services to customers.
  • Value stream map
    An illustration that uses simple graphics or icons to show the sequence and movement of information, materials, and actions in a company’s value stream.
  • VA/NVA
    (value-added to non-value-added) ratio A metric that compares the amount of time in your work process spent on value-added activities to the amount of time spent on non-value-added activities.
  • Variable costs
    Costs that vary with production or ser¬vice/sales levels, such as the costs of raw materials used in the manufacturing process. Compare to fixed costs.
  • Waste - MudaAny activity that takes time, resources, or space, but does not add value to a product or service.
  • Work combination A mixture of people, processes, ma­terials, and technology that comes together to enable the completion of a work process.
  • Workflow The steps and motions employees take to perform their work tasks.
  • Workflow (spaghetti) diagram
    A graphic that shows your organi­zation’s current equipment layout and the movement of materials and workers during work processes.
  • Work sequence
    The sequential order in which tasks that make up a work process are performed.

Six Sigma Lexicon

  • Aliasing
    Combined factors/interactions (usually in a fractional factorial experiment) for which it is not possible to distinguish the magnitude of effect contributed by each individual factor/interaction. Also Confounding
  • ANOVA - Analysis Of Variance
    A method for determining differences in mean values using the variation of the measurements.
  • Balanced Design
    A design with an equal number of experimental units in each treatment combinations or run
  • BB - Black Belt
    A Six Sigma project leader.
  • Black Belt Certification
    Recognition obtained upon satisfactory completion of 2 projects.
  • Block
    Group of homogeneous experimental units.
  • Blocking
    An experiment in which the trials &e made in some restricted order or under restricted conditions. The experiment is designed such that any nuisance factors do not confuse the true effects of the factors of interest.
  • Capability
    The ability of a process to stay within specifications and on target
  • Cause & Effect Diagrams
    A diagram to show the relationship between an effect (outcome) and its possible causes. Often displayed with five spines to group the potential causes as method, material, people, environment and machine. Asking five ‘whys’ helps to lead toward the root cause.
  • Center points
    Experimental runs with all factor levels set half way between the low and high settings. Obviously can only be done with quantitative factors.
  • CEPTS -- A formatted problem statement consisting of a description of the Conditions, Extent, Performance, Time frame, and Standards surrounding the issue.
  • Completely Randomized Design (CRD) -- An experiment in which one factor of interest is investigated (at multiple levels). The trials are made in a completely randomized order to limit the effect of uncontrollable factors.
  • Confidence Interval -- the range of response values for which one is some percent confident that the true average of the response will fall within that interval that percent of the time.
  • Degrees of Freedom for Error
    Values used in the analysis of variance to estimate the process noise. Without a good estimate of the process noise, determination of which factors are significant and to what degree may be fruitless. A rule of thumb is 5 degrees of freedom for error at a minimum this can equate to at least six replicates.
  • Defect
    Any parameter identified to be evaluated to a given standard, which fails to meet that standard.
  • DFT
    Demand Flow Technology -- Materials Management methodology that assures adequate, but not excessive availability of material at the specific time of the need -- neither early nor late.
  • Defective (part)
    A part identified to be evaluated to a given standard, which fails to meet any portion of that standard. A single defective part could have multiple defects.
  • DOA Dead on Arrival
    Product which will not work upon customer’s receipt.
  • DoE - Design of Experiments
    Any of a class of matrices (usually orthogonal) used to understand high-contribution factors. Most often associated with factorial designs.
  • Confounded Effects
    Effects which cannot be estimated independently of each other (see aliasing).
  • Confounding
    One or more effects that cannot unambiguously be attributed to a single factor or interaction.
  • Control Chart
    A methodology for identifying when a process is operating “in control” (within known statistical boundaries).
  • Cp
    Potential Capability Index -- Cp = Tolerance / 6s.
  • Cpk
    Performance Capability Index -- Cpk = min of (USL - mean) or (mean - LSL) / 3s.
  • CTQ
    Critical to Quality parameter.
  • CTQ 4-Block
    Powerful device within the Jugular process for analyzing most critical parameters/process steps vs. current knowledge.
  • CTQ Flowdown
    A very rigorous methodology for allocating requirements and assessing capabilities of the most critical segments of a product prior to M1
  • CTQ Jugular
    A process of structured and rigorous brainstorming and identification of parameters that are most critical together with an assessment of current knowledge about the process, culminating in a monitoring device for maintained success.
  • Degrees of Freedom
    Values used in the analysis of variance. Equates to the number of independent pieces of information used to estimate the variability of a factor.
  • EWMA -- Exponentially Weighted Moving Average
    a control charting methodology which utilizes historical data at an exponentially diminishing weighted value.
  • Experimental Region
    All possible factor-level combinations for which experimentation is possible. Also known as Factor Space
  • Experimental Unit
    The unit that is observed and measured during the experiment. Also known as unit of analysis.
  • F Test
    A statistical test to determine if a difference exists between two variances.
  • Factor
    an input to a process which can be changed during experimentation. Can be qualitative (e.g. type of additive) or quantitative (e.g. temperature, pressure)
  • Factor, Fixed
    If factor levels are specifically assigned, the factor is said to be fixed. Inferences generalize to only those factors. Effects are of interest.
  • Factor, Monitored
    a factor (usually uncontrollable and hence cannot be held constant) that is observed throughout the experiment and can possibly be correlated to part of the unexplained variation in the process.
  • DPU - Defects Per Unit
    (# defects found / # total units physically evaluated). - Defective Parts Per Million (outside of specification) -- (# defective units / # total units) x 1,000,000 -- based upon Cpk.
  • DPMO
    Defects Per Million Opportunities -- (# defects found / (# units) x (# opportunities per unit)) x 1,000,000.
  • Duncan's Method
    a statistical method used to determine which levels of a factor cause a change in the response. Used only after the ANOVA indicates a difference among all levels.
  • Effect
    the average change in the response when a factor is changed from a low level to a high level.
  • Error
    the inherent variability in a process. Represents the change in a response when no change in the factor is made. See noise.
  • Estimate
    a prediction of some response based on the level and impact of all factors in a process. See prediction.
  • EVOP
    Evolutionary Operation -- A method of conducting designed experiments on an ongoing process without interrupting affecting it’s efficiency.
  • Fractional 3k Designs
    all factors are run at three levels: a low, medium and high (see Fractional Factorial Designs).
  • Gage R&R
    Gage Repeatability and Reproducibility. A analysis of the percent of total variation of a distribution that can be attributed to variation in the measurement system.
  • Gage Repeatability
    Variation in the measurements obtained when one operator uses the same gage for measuring the identical characteristics of the same parts.
  • Gage Reproducibility
    Variation in the average of measurements made by different operators using the same gage when measuring identical characteristics of the same parts.
  • Generator
    An interaction effect(s) used in creating a fractional factorial design.
  • GLM
    General Linear Model -- A form of ANOVA which allows for a small degree of unbalance in the experimental design.
  • Graeco
    Latin-Square Design -- an experimental design in which one factor of interest is investigated and three nuisance factors are blocked against.
  • Factor, Nuisance
    a factor that is known to cause variability in the process; it is not desired to investigate the factor, but rather not to have the factor influence the effect of the factors of interest. See blocking.
  • Factor, Random
    If factor levels are selected randomly from a population of values, the factor is said to be Random. Variance components are of interest.
  • Full Factorial Experiment
    A class of DoE where 2 levels of several variables are explored and understanding of primary and interaction effects is obtained.
  • Fractional Factorial Experiment
    A class of DoE where 2 levels of several variables are only partially explored. Used to screen out ‘trivial many’ and allow focus on ‘vital few’ variables controlling the process.
  • Fixed Effects Factor
    a factor for which the levels are chosen selectively. For example, the effect of temperature will be investigated at 400, 450 and 500 degrees (Compare with Random Effects Factor).
  • Fractional 2k Designs
    all factors are run at a low level and a high level (see Fractional Factorial Designs).
  • HALT
    Highly Accelerated Life Testing -- One of several methods for achievement of a reliable design. Concept is to test a product to extreme (failure) conditions, find root cause of failure, improve design, and repeat the process.
  • Hetero-skedasticity unequal variances
    This condition when applied to factor levels may affect the conclusions from ANOVA.
  • Histogram
    A bar chart to show the distribution of the collected data.
  • Hyper-Graeco-Latin Square Design
    an experimental design in which one factor of interest is investigated and four nuisance factors are blocked against.
  • Hypothesis
    an assertion that is tested using a statistical technique. The hypothesis will either be rejected or insufficient evidence will be available to reject.
  • Interaction
    a condition in which the effect of the level of a factor on a response is different for different levels of a second factor. There are two-way interactions, three-way interactions, etc.
  • IX-MR
    Individual X and Moving Range -- a control chart of sequential data points, together with a chart of ranges between points.
  • Kurtosis
    Provides a measure of peakedness of the distribution - The 4th moment around the mean .
  • Latin Square Design (LSD)
    an experimental design in which one factor of interest is investigated and two nuisance factors are blocked against.
  • Level
    A setting or value of a factor. Can be qualitative (e.g. additive A and additive B) or quantitative (e.g. 1000psi, 2000 psi.)
  • Main Effect
    The change in a response that occurs when a factor is changed from its low level to its high level.
  • MBB
    Master Black Belt -- A Six Sigma trainer and project mentor.
  • Mean
    Measure of central tendency of a variable- The first moment around the origin.
  • Mean Square
    a column in the ANOVA table that represents the variance of a response due to different sources of variability.
  • Mean Square Error
    an entry in the ANOVA table that represents the variance of a response at a given levels of all factors. An estimate of the variance of a response due to noise (error).
  • Minitab
    GE’s current statistical analysis software application of choice.
  • Multiple Comparison Procedure
    a statistical method used to determine which levels of a factor cause a change in the response. Used only after the ANOVA indicates a difference among all levels. Examples are Fisher's method, Duncan's method, Scheffe's method.
  • Multi-Vari Analysis
    A graphical method of decomposing the sources of process variation into their basic components. This technique is an early step in removing some of the trivial many and preparing a sub-set of factors for designed experimentation.
  • Multivariate Statistical Methods
    Statistical tools for analyzing a set of variables to determine their influence on several responses. Includes a wide class of statistical tools such as regression, principle components, factor analysis, clustering, discriminent analysis.
  • Nested Design
    an experimental design in which a one factor has different level settings depending on the level of another variable. For example, batches within different suppliers, levels of competing additives, etc,
  • Noise
    the inherent variability in a process. Represents the change in a response when no change in the factor is made. See error.
  • Normal Distribution
    a bell-shaped curve of probabilities that describe many natural processes. Can occur also in situations in which replicates are taken and are averaged
  • Normal Probability Plot
    a graphical method for investigating whether a sample might have come from a population with a normal distribution. Often used to check the validity of using ANOVA.
  • One-Way ANOVA
    analysis of variance for investigating a single factor at multiple levels. See ANOVA.
  • Optimization
    Finding the combination of factors and levels that produces the most desirable output from a process.
  • Pareto Chart
    A bar chart to display events with respect to a common metric (# of times, $, time, etc.).
  • Plackett-Burman Design
    a designed experiment used in screening experimentation in which a minimal number of trials are needed. Typically only main effects are investigated with no estimate of the interaction effects.
  • Randomization
    Mixing up the order of the runs in an experiment as completely as is practical.
  • Randomized Block Design
    an experiment in which one factor of interest is investigated and one nuisance factor is blocked against.
  • Repetition
    Running several experimental units over one treatment combinations. Contrast with Replication
  • Replication
    repeated runs at the same experimental conditions; provides an estimate of the noise in the process.
  • Residuals
    the difference between the observed response and the predicted response for a given set of factor conditions. Used in model validation and process investigation.
  • Resolution
    a description of fractional factorial designs that gives the degree to which factors will be aliased with other factors' interactions.
  • Response
    an output from the process which will be measured during the experiment.
  • RSM
    Response Surface Methodology -- A class of designed experiments where curvature of the vital few is examined and understood. Subsets include central composite designs with star or face points.
  • R-Square
    percent of variability in the response explained by the controlled factors.
  • Run
    a set of process conditions defined by specifying levels of all the factors in the experiment. Also known as a Treatment Combination.
  • Point Estimate
    the best single value estimate of some prediction or mean response- Should be used in conjunction with confidence and/or prediction intervals.
  • Pre-control
    A methodology for establishing statistically sound probabilities of goodness when a process is starting.
  • PRD
    Phase Review Discipline -- A rigorous methodology for new product introduction which includes milestones at critical points.
  • Prediction
    a best estimate of some response for a given set of levels for all factors.
  • Prediction Interval
    the range of values for a response of which one is some percent confident that a future observation will fall within. See Confidence Interval.
  • Process Demographics
    The list of conditions/states of various factors during the time a response is generated. These help us to understand what area of the process may be driving the problem.
  • Random Effects Factor
    a factor for which the levels are chosen at random from a definable population. For example, the effect of batches will be investigated by randomly choosing five batches. (Compare with Fixed Effects Factor).
  • Standard Deviation (s, sigma)
    A statistical calculation used to characterize the variability of a set of data. It is the square root of the variance.
  • T-Test
    A statistical comparison of mean values of a sample, assuming a normal population.
  • Trivial Many
    The factors that have long been thought to have some influence on the process but really account for very little of the variation in performance.
  • Treatment Combination
    a set of process conditions defined by specifying levels of all the factors in the experiment. Also known as a Run.
  • Two-Way ANOVA
    analysis of variance for investigating two factors at multiple levels
  • Two-way Interaction Plot
    a scatter plot of the average responses (vertical axis) as a factor of one factor (horizontal axis) and the average responses for each level of a second factor connected by lines.
  • Type I Error
    the error of assuming that the hypothesis is false when in fact it is true. Associated probability is labeled a.
  • Type II Error
    the error of assuming that the hypothesis is true when in fact it is false. Associated probability is labeled b.
  • Run chart
    A sequential time series plot of data which provides some statistical analysis capabilities and probabilities.
  • Scatter Plot
    A chart (dot plot) to show the relationship between two variables.
  • SCN
    Supplier Change Notice -- The communication device for requesting a change to a purchased part, initiated either by a Supplier to GEMS, or by GEMS to a Supplier.
  • Screening Experiment
    a technique used to characterize a process (usually assumes linear changes in the response for a change of factor levels) (compare with RSM).
  • Signal to Noise Ratio
    a ratio that depends on the variability in the response due to changing factor levels relative to the variability when there is no change in the factor level.
  • (Six) 6-s process
    A stable process operating such that its output has a minimum Cpk of 1.5.
  • Skewness
    a condition in which the normal distribution is shifted to the left or right, that is, no longer symmetric. Can influence the validity of using ANOVA.
  • SPC - Statistical Process Control
    Used to monitor process stability preferably after after modification to desired state.
  • Unbalanced Design
    A design with an unequal number of experimental units in each treatment combinations or run
  • USL or LSL - Upper (Lower) Specification Limit
    boundaries of design criteria.
  • UCL or LCL - Upper (Lower) Control Limit
    the statistical boundaries of a control chart. - Upper (Lower) Confidence Limit -- (used in T-test, ANOVA, etc).
  • Variance
    Provides a measure of dispersion. The square root of the variance is the standard deviation. The 2nd moment around the mean.
  • Vital Few
    The factors that are critical in controlling the process
  • ZB
    Z benchmark, Zst, short term sigma -- Assumes process is centered (on target) with short term variation.
  • Z value
    Calculation of how many sigmas fit between the process output average and the closest specification limit.

Kano's Law: Wat vandaag goed genoeg is, is morgen niet meer goed genoeg.