Official Six Sigma Certifications

Measure Phase in Six Sigma: DMAIC Measurement Systems

The Measure Phase in Six Sigma is an important part of problem-solving. It involves capturing key information about current practices to help inform improvements. The details matter. Accurate, relevant and reliable measurements help you understand the problems in a process and identify opportunities to improve it. Start with clear definitions and a practical data collection plan.

The Measure Phase in Six Sigma aims to gather critical data that provides insights into process performance and variation. It involves identifying key measures, collecting relevant information, and conducting analysis to understand the current state of processes, setting a foundation for subsequent improvement initiatives.

The DMAIC Measurement Systems

This section explains the sources of measurement-system variation and helps you choose an appropriate analysis for continuous or discrete data.

Measurement System Analysis (MSA) for Data Types

For continuous measurements, a gage repeatability and reproducibility (R&R) study helps assess:
  • % Tolerance
  • % Contribution
  • Number of Distinct Categories
For discrete or categorical assessments, an attribute agreement study can assess:
  • Accuracy
  • Repeatability
  • Reproducibility
A suitable measurement study and statistical software can estimate these measures. Percentage tolerance compares measurement study variation with the specification width. Percentage contribution compares a measurement variance component with total variance. Percentage study variation uses standard deviations, not variances. These percentages have different denominators and are not interchangeable. The example screening bands below must be checked against the application’s documented measurement plan.


Sources of observed variationEnglish teaching artwork. Sources of observed variation. Observed process variation Measurement system Actual process Appraisers Instruments Methods and conditions Controllable factors Uncontrollable factors MSA characteristics Bias / accuracy Stability Linearity Repeatability Reproducibility Assess these characteristics across the measurement system; they are not five additive instrument variance components.Sources of observed variationObserved processvariationMeasurement systemActual processAppraisersInstrumentsMethods andconditionsControllable factorsUncontrollablefactorsMSA characteristicsBias / accuracyStabilityLinearityRepeatabilityReproducibilityAssess these characteristics across the measurement system; they are not five additive instrument variance components.
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Six Sigma Components of Variation


Observed variation reflects both actual process variation and measurement error. Process variation may arise from factors we can control and factors that are difficult to control.

Measurement error can arise from appraisers, instruments, methods and conditions. Measurement system analysis examines bias and accuracy, stability, repeatability, reproducibility and linearity. Reproducibility includes differences between appraisers; it is not solely an instrument property.

Observed variance = actual process variance + measurement-error variance, when process values and measurement errors are uncorrelated.

For an additive model, observed value equals process value plus measurement error. Variances add when the two components are uncorrelated. If they are correlated, the variance also includes twice their covariance. Standard deviations do not add in the same way.


Process and measurement-error varianceEnglish teaching artwork. Process and measurement-error variance. True process Measurement error Observed measurements Density Value Uncorrelated additive errors: variances add; standard deviations do not. Uncorrelated additive errors: variances add; standard deviations do not. Observed variance = process variance + measurement-error variance. Bias and correlation require separate consideration. Illustrative probability densities use a common value and density scale.Process and measurement-error varianceTrue processValueMeasurement errorValueObserved measurementsValueDensityUncorrelated additive errors: variances add; standard deviations do not.Observed variance = process variance + measurement-error variance. Bias and correlation requireseparate consideration.Illustrative probability densities use a common value and density scale.
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Six Sigma Process Variation


Observed spread and true process spreadEnglish teaching artwork. Observed spread and true process spread. LSL USL Observed spread True process spread Value Density Illustrative specification limits; measurement error broadens observed spread. Illustrative specification limits; measurement error broadens observed spread. Specification limits describe requirements; they are distinct from control limits.Observed spread and true process spreadDensityLSLUSLValueObserved spread · solid tealTrue process spread · dashedIllustrative specification limits; measurement error broadens observed spread.Specification limits describe requirements; they are distinct from control limits.
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Six Sigma Observed Variation vs True Variation


In the above example, LSL – Lower Specification Limit and USL – Upper Specification Limit.

Measurement System Analysis

Measurement system errors can be due to:
  • Accuracy – Closeness to a reference value. The difference between the average measurement and the reference value is bias.
  • Repeatability – Variation when the same appraiser measures the same characteristic on the same part repeatedly with the same instrument under the same conditions.
  • Reproducibility – Variation between appraisers measuring the same characteristic on the same parts with the same instrument and procedure.
  • Stability – Change in measurement performance, such as bias, over an extended period under a defined measurement procedure.
  • Linearity – Change in measurement bias across the instrument’s measurement range.

Acceptable Level of Measurement System Variation (Rules of Thumb)


Example screening bands: interpret each measure independently and confirm the criteria in your measurement plan. Percent tolerance and percent contribution use different denominators.

DecisionMeasurement %ToleranceMeasurement %ContributionNumber of distinct categories
AcceptableLess than 8%Less than 2%More than 10
Evaluate risk8% to 30%, inclusive2% to 7.7%, inclusive4 to 10, inclusive
UnacceptableMore than 30%More than 7.7%Fewer than 4
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Six Sigma Gage R&R Thumb Rule – Continuous Data


These example bands retain strict greater-than and less-than rules. At exactly 90%, review the documented measurement-plan criterion; do not assume an automatic pass or fail.

DecisionAccuracy / agreement with referenceRepeatability / within-appraiser agreementReproducibility / between-appraiser agreement
AcceptableMore than 90%More than 90%More than 90%
UnacceptableLess than 90%Less than 90%Less than 90%
Boundary reviewExactly 90%: apply the documented criterionExactly 90%: apply the documented criterionExactly 90%: apply the documented criterion
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Six Sigma Attribute R&R Thumb Rule – Discrete Data


Process Variation

Common-cause variation is the background variation inherent in the current process. A stable process exhibits a consistent, predictable pattern of variation. Special causes are departures from that pattern and should be investigated. A control-chart signal provides evidence of possible instability; a signal alone does not establish the specific cause.

Data Interpretation

Data is interpreted using factors such as Stability, Normality, Shape, Spread and Centering.

A run chart plots measurements in the order collected. It helps you assess stability and look for patterns that warrant investigation. Use an appropriate, predefined rule or runs test and consider the process context before attributing a pattern to a special cause.

The following schematics illustrate repeated values, clustering, mixtures, oscillation, trends and shifts around a reference median. Their qualitative patterns are teaching examples, not fitted results or calculated significance tests.

Run Chart – Same Value Plot

Seven or more identical consecutive values are a screening signal in this example. Investigate possible rounding, limited measurement resolution, data recording practices or a process change. Repeated values alone do not prove bias.


Run chart · repeated valuesEnglish teaching artwork. Run chart · repeated values. Measurement Time Reference median Eight consecutive equal values are highlighted. Check resolution, rounding, recording practices and the process; identical values alone do not prove bias. Illustrative run pattern. Eight consecutive equal values are highlighted. Check resolution, rounding, recording practices and the process; identical values alone do not prove bias. Illustrative run pattern.Run chart · repeated valuesMeasurementReferencemedianTimeEight consecutive equal values are highlighted.Check resolution, rounding, recording practices and the process; identical values alone do not provebias.Illustrative run pattern.
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Six Sigma Run Chart – Same Value Plot


Run Chart – Clustering Plot

Clustering produces comparatively few runs about the median: groups of consecutive points remain on one side before crossing. Possible explanations include lot-to-lot or setup differences and measurement or sampling issues. Investigate the process rather than assuming a cause from the pattern alone.


Run chart · clusteringEnglish teaching artwork. Run chart · clustering. Measurement Time Reference median Clustering: comparatively few runs about the reference median. Investigate possible lot, setup, measurement or sampling effects. Illustrative run pattern. Clustering: comparatively few runs about the reference median. Investigate possible lot, setup, measurement or sampling effects. Illustrative run pattern.Run chart · clusteringMeasurementReferencemedianTimeClustering: comparatively few runs about the reference median.Investigate possible lot, setup, measurement or sampling effects.Illustrative run pattern.
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Six Sigma Run Chart – Clustering Plot


Run Chart – Mixtures Plot

Mixtures produce comparatively many runs about the median, with frequent crossings and relatively few points near the center. Combining populations or sampling from processes at different levels can produce this pattern. The rule of fourteen or more alternating increases and decreases concerns oscillation, described next; it is not a general definition of a mixture.


Run chart · mixturesEnglish teaching artwork. Run chart · mixtures. Measurement Time Reference median Mixtures: comparatively many crossings of the reference median. Check whether observations combine populations or processes at different levels. Illustrative run pattern. Mixtures: comparatively many crossings of the reference median. Check whether observations combine populations or processes at different levels. Illustrative run pattern.Run chart · mixturesMeasurementReferencemedianTimeMixtures: comparatively many crossings of the reference median.Check whether observations combine populations or processes at different levels.Illustrative run pattern.
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Six Sigma Run Chart – Mixtures Plot


Run Chart – Oscillation Plot

Oscillation is frequent alternation between increases and decreases in consecutive measurements. Fourteen alternating points are one commonly used screening rule. Oscillation may suggest over-adjustment, systematic sampling or another influence, but the chart alone does not identify the cause.


Run chart · oscillationEnglish teaching artwork. Run chart · oscillation. Measurement Time Reference median Oscillation: frequent changes between increases and decreases. Fourteen alternating points are one screening convention, not an automatic result inferred from this sketch. Illustrative run pattern. Oscillation: frequent changes between increases and decreases. Fourteen alternating points are one screening convention, not an automatic result inferred from this sketch. Illustrative run pattern.Run chart · oscillationMeasurementReferencemedianTimeOscillation: frequent changes between increases and decreases.Fourteen alternating points are one screening convention, not an automatic result inferred from thissketch.Illustrative run pattern.
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Six Sigma Run Chart – Oscillation Plot


Run Chart – Trend Plot

A sustained sequence of increasing or decreasing observations indicates a trend. This lesson uses seven consecutive points as a screening rule. Investigate possibilities such as wear, environmental drift or changes in measurement methods. The exact rule should be specified before examining the data.


Run chart · trendsEnglish teaching artwork. Run chart · trends. Measurement Time Reference median Upward trend Downward trend Seven rising and eight falling measurements are highlighted. Illustrative run pattern. Seven rising and eight falling measurements are highlighted. Illustrative run pattern.Run chart · trendsMeasurementReferencemedianTimeUpward trendDownward trendSeven rising and eight falling measurements are highlighted.Illustrative run pattern.
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Six Sigma Run Chart – Trend Plot


Run Chart – Shift Plot

Eight consecutive points on the same side of a reference median are the screening rule used here for a possible shift. A shift is a change in process level; it need not occur gradually. Use the selected rule and process knowledge to investigate it.


Run chart · shiftEnglish teaching artwork. Run chart · shift. Measurement Time Reference median A shift is a change in process level; it need not be gradual. Eight consecutive points above the reference median are highlighted. Illustrative run pattern. A shift is a change in process level; it need not be gradual. Eight consecutive points above the reference median are highlighted. Illustrative run pattern.Run chart · shiftMeasurementReferencemedianTimeA shift is a change in process level; it need not be gradual.Eight consecutive points above the reference median are highlighted.Illustrative run pattern.
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Six Sigma Run Chart – Shift Plot


Introduction to Normal Distribution

The normal distribution, also called Gaussian, is associated with the mathematician and astronomer Carl Friedrich Gauss and his work on observational errors. Abraham de Moivre had derived the normal approximation to the binomial distribution earlier, in 1733. The model is widely used, but its suitability depends on the data and context. Examples that may be approximately normal within a defined population include:
  • Human characteristics such as weight, height and IQ, within an appropriately defined population
  • Physical process outputs, including yield measurements when a normal approximation is appropriate

Normal distribution · mean and standard deviationEnglish teaching artwork. Normal distribution · mean and standard deviation. Mean = 100 Standard deviation = 10 One standard deviation = 10 units Value Density The tails continue beyond the plotted range. Mean = 100 · Standard deviation = 10. The tails continue beyond the plotted range.Normal distribution · mean and standard deviationDensity708090100110120130ValueOne standard deviation = 10 unitsMean = 100 · Standard deviation = 10.The tails continue beyond the plotted range.
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Six Sigma Normal Distribution - 1


A normal distribution is continuous, symmetric and bell-shaped. It is characterized by its mean μ and standard deviation σ; notation often writes N(μ, σ²) using the variance. Values near the mean have the greatest density. The tails approach zero without ending, and the total area under the probability-density curve is one.

Nonnormal data may be skewed, heavy-tailed, multimodal or have another shape. A symmetric appearance alone does not establish normality, and a histogram’s appearance depends partly on its bins and sample size.


Centered normal coverage within one to six standard deviationsEnglish teaching artwork. Centered normal coverage within one to six standard deviations. Centered normal model Standard deviations from the mean Two-sided coverage Mean For long-term Six Sigma estimates, state any 1.5-SD shift assumption separately. Standard deviations from the mean. Percentages are rounded to the shown precision. For long-term Six Sigma estimates, state any 1.5-SD shift assumption separately.Centered normal coverage within one to six standard deviationsCentered normal model · Two-sided coverageMean68.27%−1 SD+1 SD95.45%−2 SD+2 SD99.73%−3 SD+3 SD99.9937%−4 SD+4 SD99.999943%−5 SD+5 SD99.99999980%−6 SD+6 SDStandard deviations from the mean. Percentages are rounded to the shown precision.For long-term Six Sigma estimates, state any 1.5-SD shift assumption separately.
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Six Sigma Normal Distribution - 2


For a centered normal model, the proportions within one, two and three standard deviations of the mean are approximately 68.27%, 95.45% and 99.73%. The corresponding coverage within four, five and six standard deviations is approximately 99.9937%, 99.999943% and 99.99999980%. These are two-sided, centered-model probabilities. They are distinct from the conventional Six Sigma long-term calculation using a 1.5-standard-deviation shift.

Use plots and an appropriate test, such as the Anderson–Darling normality test, to assess compatibility with a normal model. At a preselected significance level of 0.05, a small p-value provides evidence against normality. A larger p-value means insufficient evidence to reject normality; it does not prove that the population is normal. The hypotheses are:
  • H0 – The population distribution is normal
  • Ha – The population distribution is not normal

Distribution shape · Symmetric normalEnglish teaching artwork. Distribution shape · Symmetric normal. Density Value Center: mean and median coincide in this model. Spread: standard deviation. Assess normality from observations, probability plots and an appropriate test. Illustrative density. Assess sample normality using actual observations and an appropriate test. Center: mean and median coincide in this model. Spread: standard deviation. Assess normality from observations, probability plots and an appropriate test. Illustrative density. Assess sample normality using actual observations and an appropriate test.Distribution shape · Symmetric normalDensitySDMeanValueCenter: mean and median coincide in this model.Spread: standard deviation.Assess normality from observations, probability plots and an appropriate test.Illustrative density. Assess sample normality using actual observations and an appropriate test.
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Six Sigma Histogram Distribution Symmetrical Shape


Distribution shape · Right-skewedEnglish teaching artwork. Distribution shape · Right-skewed. Density Value Center: median is a useful robust summary; report the mean where relevant. Quartiles: Q1 is the 25th percentile; Q3 is the 75th. Spread: IQR = Q3 − Q1. Assess process stability using time-ordered observations. Illustrative density. Assess sample normality using actual observations and an appropriate test. Center: median is a useful robust summary; report the mean where relevant. Quartiles: Q1 is the 25th percentile; Q3 is the 75th. Spread: IQR = Q3 − Q1. Assess process stability using time-ordered observations. Illustrative density. Assess sample normality using actual observations and an appropriate test.Distribution shape · Right-skewedDensityQ1 (25%)MedianQ3 (75%)ValueCenter: median is a useful robust summary; report the mean where relevant.Quartiles: Q1 is the 25th percentile; Q3 is the 75th. Spread: IQR = Q3 − Q1.Assess process stability using time-ordered observations.Illustrative density. Assess sample normality using actual observations and an appropriate test.
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Six Sigma Histogram Distribution Positively Skewed Shape


Distribution shape · Left-skewedEnglish teaching artwork. Distribution shape · Left-skewed. Density Value Center: median is a useful robust summary; report the mean where relevant. Quartiles: Q1 is the 25th percentile; Q3 is the 75th. Spread: IQR = Q3 − Q1. Assess process stability using time-ordered observations. Illustrative density. Assess sample normality using actual observations and an appropriate test. Center: median is a useful robust summary; report the mean where relevant. Quartiles: Q1 is the 25th percentile; Q3 is the 75th. Spread: IQR = Q3 − Q1. Assess process stability using time-ordered observations. Illustrative density. Assess sample normality using actual observations and an appropriate test.Distribution shape · Left-skewedDensityQ1 (25%)MedianQ3 (75%)ValueCenter: median is a useful robust summary; report the mean where relevant.Quartiles: Q1 is the 25th percentile; Q3 is the 75th. Spread: IQR = Q3 − Q1.Assess process stability using time-ordered observations.Illustrative density. Assess sample normality using actual observations and an appropriate test.
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Six Sigma Histogram Distribution Negatively Skewed Shape


Distribution shape · Long-tailedEnglish teaching artwork. Distribution shape · Long-tailed. Density Value Center: median. Spread: a defined percentile span, such as P95 − P5. Use a model and summary measures suited to the observed tails. Illustrative density. Assess sample normality using actual observations and an appropriate test. Center: median. Spread: a defined percentile span, such as P95 − P5. Use a model and summary measures suited to the observed tails. Illustrative density. Assess sample normality using actual observations and an appropriate test.Distribution shape · Long-tailedDensity5th percentileMedian95th percentile90% span: P95 − P5ValueCenter: median.Spread: a defined percentile span, such as P95 − P5.Use a model and summary measures suited to the observed tails.Illustrative density. Assess sample normality using actual observations and an appropriate test.
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Six Sigma Histogram Distribution Long Tailed Shape


Distribution shape · Symmetric bimodalEnglish teaching artwork. Distribution shape · Symmetric bimodal. Density Value Investigate whether the modes represent distinct processes or populations. Justify process groups before comparing their summaries. Illustrative density. Assess sample normality using actual observations and an appropriate test. Investigate whether the modes represent distinct processes or populations. Justify process groups before comparing their summaries. Illustrative density. Assess sample normality using actual observations and an appropriate test.Distribution shape · Symmetric bimodalDensityValueInvestigate whether the modes represent distinct processes or populations.Justify process groups before comparing their summaries.Illustrative density. Assess sample normality using actual observations and an appropriate test.
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Six Sigma Histogram Distribution Bi-Modal Symmetrical Shape


Distribution shape · Multimodal with a longer left tailEnglish teaching artwork. Distribution shape · Multimodal with a longer left tail. Density Value Several modes can coexist with skewness. Investigate process/population groups and justify segmentation before interpreting group summaries. Illustrative density. Assess sample normality using actual observations and an appropriate test. Several modes can coexist with skewness. Investigate process/population groups and justify segmentation before interpreting group summaries. Illustrative density. Assess sample normality using actual observations and an appropriate test.Distribution shape · Multimodal with a longer left tailDensityValueSeveral modes can coexist with skewness.Investigate process/population groups and justify segmentation before interpreting group summaries.Illustrative density. Assess sample normality using actual observations and an appropriate test.
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Six Sigma Histogram Distribution Multi-Modal Negatively Skewed Shape


What do I do when data is Non Normal?

When data are nonnormal, first consider the process, study design, mixture of populations and suitable statistical method. A transformation may help when it is appropriate for the question; not every analysis requires normal raw data. Options include:
  • Take a logarithm of positive measurements, using a specified base.
  • Apply a suitable power transformation, checking its domain and monotonicity.
  • Use a reciprocal transformation, 1/y, only where values are nonzero and the interpretation is appropriate.
When transforming data, take the following precautions:
  • Apply the same transformation to the specification limits. If the transformation reverses order, reverse the transformed lower and upper limits accordingly.
  • Use the chosen scale consistently in the analysis, and explain how estimates and conclusions relate back to the original measurement scale.
  • Check data quality, consistency, sampling and the method’s assumptions before transforming. More observations do not make a nonnormal population normal; additional representative data may instead clarify its shape. Consider a suitable nonnormal or nonparametric analysis where appropriate.

Understanding the Measure Phase in Six Sigma

The Measure phase in Six Sigma is a crucial stage that sets the tone for the entire process improvement initiative. Visualize this phase as a compass, guiding you through your organization's processes with precision. Here, the focus lies in gathering comprehensive information about the current processes involved in a problem. However, it's not just about collecting any information; it's about identifying and defining key metrics that matter, such as customer requirements, organizational goals, or critical performance indicators.

One of the key considerations when selecting measurement methods is their relevance to customer requirements, support of improvement and organizational goals, data accuracy, availability, and ease of data collection. This underscores the significance of aligning the measurements with what truly matters to your customers and your organization's strategic objectives. It's not just about gathering data for the sake of it; it's about capturing insights that can drive meaningful improvement. This attentiveness to relevancy separates effective measurement systems from superficial data collection exercises.

In addition to identifying important metrics, it's essential to understand the variation arising from the measurement system itself. This leads us to the concept of Measurement System Analysis (MSA), which assesses the accuracy, repeatability, reproducibility, and linearity of the measurement system. All these factors contribute to understanding how reliable our measurements are and if they are capturing true variability in our processes.

When it comes to variation, there are two primary sources to consider - actual process variation and variation from the measurement system. Both can significantly impact our understanding of how our processes are functioning and where improvements can be made. By delving deep into these variations, we uncover nuances that might be hidden from plain sight but can have a profound impact on our ability to enhance operational efficiency and product quality.
A real-world example of this would be examining customer satisfaction levels in a service industry using various data collection techniques like surveys, interviews, and customer feedback logs. Each method has its own strengths and weaknesses, with different degrees of impact on customer perceptions and insights that can guide targeted improvements.

The Measure Phase may seem like an elaborate exercise in data collection, but its significance cannot be overstated. It acts as a powerful diagnostic tool that uncovers critical areas for process improvement, armed with objective insights and clear visibility into process dynamics.

Transitioning from comprehending the intricacies of measurement to harnessing the power of collected data presents a compelling narrative that unfolds in the next section—the vital role played by data collection in enhancing process measurement.

Importance of Data Collection in Measure Phase

In the world of process improvement, data is akin to a treasure map, guiding organizations toward buried opportunities for enhancement by providing a clear picture of where to direct their efforts. The Measure Phase depends on gathering accurate, relevant, and reliable data to truly comprehend the current state of a process. By doing so, it sets the stage for identifying areas in need of improvements and scrutinizing the root causes behind performance issues.

Now, imagine embarking on a journey without a map or any knowledge of your surroundings. Attempting process improvements without adequate data would be akin to navigating unknown terrain blindly. Data serves as a guiding light, illuminating the operational excellence that can be achieved. Without it, decisions are mere estimations, and change efforts lack concrete direction.

Moreover, in an environment driven by evidence-based decision-making, data stands as the bedrock upon which strategies are built. It provides credibility to improvement initiatives, enabling stakeholders to advocate for change with solid numbers and trends rather than abstract assumptions.

To illustrate this further, think of data collection as assembling puzzle pieces. Each piece represents a different aspect of the process - its strengths, weaknesses, and potential bottlenecks. As more pieces are added (data collected), a clearer image of the overall situation emerges. This complete picture empowers organizations to pinpoint precise areas for improvement and create targeted solutions.

Consider an organization seeking to streamline its manufacturing process to reduce defects. Data collection would entail gathering information on defect rates, production times, machine downtime, and other relevant metrics. This comprehensive data would provide insights into specific stages of the process that require attention and aid in devising effective corrective measures.
As demonstrated, data collection serves as the compass that guides improvement endeavors in the Measure Phase. It is not just about accumulating numbers; rather, it is about leveraging these numbers to steer processes toward peak performance.


Measure Phase in Six Sigma DMAIC
Measure Phase in Six Sigma DMAIC


Performance Measures and Their Selection

The Measure Phase in a Six Sigma process is vital, focusing on gathering information to understand how a process is performing. Choosing the right performance measures is crucial as they provide insight into the effectiveness and efficiency of the processes being analyzed. These measures act as the scales used to weigh progress and pinpoint areas needing improvement.

Defect Rates: Defect rates describe errors or defects relative to a defined denominator, such as units, opportunities or exposure time. Keep the denominator consistent when comparing rates. Tracking them helps you assess quality, identify patterns and decide where to improve.

For instance: A product manufacturing unit may measure defect rates to understand and minimize production errors, ultimately enhancing product quality and reducing rework costs.

Customer Satisfaction Scores

Another essential performance measure is customer satisfaction scores. These scores reflect how well a business meets customer expectations across various touchpoints, such as service delivery, product quality, and support.

Customer satisfaction scores are valuable indicators for service-oriented businesses like restaurants, where feedback from customers can directly impact operational improvements. A high score reflects positively on the business's performance, while a drop indicates potential areas for refinement.

It's important to note that while these performance measures are valuable, selecting them should align closely with customer requirements, organizational goals, and improvement efforts. Metrics such as cycle times for processes can help in understanding the time taken at each step, vital for identifying bottlenecks and inefficiencies.

Apart from these key performance indicators (KPIs), other factors like data accuracy, availability, ease of collection, and relevance to organizational objectives play a significant role in their selection. The chosen metrics should not only shed light on current process performance but also support future improvement initiatives.
The careful selection of performance measures acts as a compass guiding organizations towards targeted improvements in their processes. Now let's explore how these measures feed into the broader process improvement framework.

Techniques for Analyzing Data

When gathering data to understand process performance, it's time to put the data under the microscope and extract valuable insights. Several techniques used in Six Sigma effectively analyze data, each serving a unique purpose in revealing trends, patterns, and relationships within the collected data.

Control Charts

Control charts are one of the primary tools utilized in the Measure Phase of Six Sigma. Their purpose lies in monitoring process stability over time by plotting data points based on a specific measure. This allows for the identification of variations or abnormalities. Control limits and predefined signal rules help distinguish routine variation from unusual patterns. Control limits are estimated from process behavior; they are not customer specification limits.

Process Mapping

Another vital technique used in Six Sigma is process mapping, which visually represents and analyzes a process from start to finish. It provides a comprehensive view of the steps involved, their interrelations, input-output dependencies, and potential areas for improvement. Through process mapping, it becomes possible to identify bottlenecks, redundancies, and inefficiencies for enhancement.

Cause-and-Effect Diagrams

Cause-and-effect diagrams, also known as fishbone diagrams or Ishikawa diagrams, serve as powerful analytical tools used to identify potential causes for a specific effect or problem. They help break down complex issues into more digestible components, making it easier to recognize contributing factors and their interrelationships. In the context of the Measure Phase, cause-and-effect diagrams are instrumental in pinpointing potential sources of variation and deviations within the process.

Utilizing these analytical techniques enables organizations to gain a comprehensive understanding of their processes and identify opportunities for optimization, setting the stage for meaningful improvement initiatives as they progress through the Six Sigma methodology.

These techniques collectively contribute to uncovering actionable insights from data analysis, facilitating informed decision-making and targeted process improvements within the Measure Phase of Six Sigma.

Ensuring Measurement System Accuracy in Six Sigma

In Six Sigma, ensuring that the measurement system is accurate is like laying a strong, stable foundation for a building. If the foundation has flaws, the whole structure is compromised. The same goes for measurements in a process improvement project - if the data is not reliable, then any decisions or improvements made based on that data might not lead to the desired outcomes.

Measurement System Analysis (MSA) evaluates the performance and dependability of a measurement system. It separates measurement effects from part-to-part or process variation and examines instruments, appraisers, procedures and conditions. It also supports an assessment of measurement uncertainty.

Measurement System Analysis (MSA) Fundamentals

The basics of MSA involve determining the number of assessors and sample parts, ensuring assessors have knowledge of methods, selecting sample elements properly, and using proper measuring instruments with sufficient resolution/discrimination.

One key part of this analysis is the Gauge R&R Study, which assesses repeatability and reproducibility. If several people measure the same object with the same instrument, differences may reflect appraisers, the procedure or the instrument. A designed study helps quantify these effects rather than assuming that any difference proves a problem.
For instance, let's say we're manufacturing computer casings. We would perform a Gauge R&R Study by having multiple operators measure sample sheet metal casings with varying characteristics. We then compare these measurements to see if there are differences among the operators. This can help us uncover whether there are issues with variability in measurements or if certain operators consistently produce different results.

A well-designed study helps you decide whether the measurement system is suitable for the intended application and whether it can distinguish relevant process differences. It supports reliable analysis; it does not guarantee that every subsequent conclusion is valid.

Now that we've laid out why ensuring accuracy in our measurement system is crucial, let's delve into some common tools and techniques used in MSA to achieve this.


Measure Phase in Six Sigma DMAIC - Measurement Systems
Measure Phase in Six Sigma DMAIC - Measurement Systems


Actions and Results Verification in Measure Phase

Once data has been collected, it's essential to thoroughly verify the validity and reliability of the information obtained. This verification process encompasses several crucial components that ensure the integrity of the analysis and subsequent improvement efforts. Let's break down these components to gain a comprehensive understanding of this critical phase.

First and foremost, it's imperative to review the data collection process itself. This involves assessing the methods used to gather information, ensuring that they align with established best practices and effectively capture essential process elements. By conducting a rigorous evaluation of the data collection methods, potential biases or inaccuracies can be identified and rectified early on, bolstering the credibility of the subsequent analysis.

In addition to scrutinizing the data collection methods, it is equally essential to evaluate the chosen metrics against the process performance. The selected metrics should directly reflect the critical aspects of the process under examination, enabling an accurate assessment of its performance and facilitating informed decision-making. By confirming the alignment between chosen metrics and process intricacies, organizations can confidently proceed with implementing targeted improvements based on substantiated evidence.
Another pivotal aspect of actions and results verification in the Measure Phase is ensuring that areas earmarked for improvement are supported by empirical evidence. This entails a meticulous examination of the data to pinpoint performance shortcomings and areas ripe for enhancement. By corroborating observed deficiencies with concrete data, organizations can confidently prioritize improvement initiatives, knowing that their decisions are rooted in factual insights rather than assumptions.

Moreover, this verification encompasses a comprehensive validation of all findings against established benchmarks and industry standards. The data must withstand scrutiny against established norms, ensuring that any identified variances from expected performance levels are grounded in robust evidence. By subjecting findings to such scrutiny, organizations safeguard against unwarranted conclusions and lay a solid foundation for subsequent improvement endeavors.

By closely scrutinizing each facet of data collection and analysis, organizations can instill confidence in their findings and bolster the effectiveness of their improvement initiatives. It is through this rigorous verification process that organizations pave the way for targeted, impactful interventions that drive substantive enhancements in operational efficiency and overall performance.

Ensuring the accuracy and reliability of data is foundational in achieving successful process improvements. Through meticulous verification, organizations can make informed decisions that lead to tangible enhancements across their operations.

Frequently Asked Questions for Measure Phase in Six Sigma

What are some common challenges faced during the measure phase?

Answer: Some common challenges faced during the measure phase in Six Sigma include data collection errors, lack of clarity in defining metrics, and difficulty in establishing a baseline for process performance. These challenges can lead to inaccurate analysis and flawed decision-making. According to a study by the International Six Sigma Institute, 42% of organizations reported facing challenges related to collecting accurate and reliable data during the measure phase, highlighting the significance of this issue.

What are the main objectives of the measure phase in Six Sigma?

Answer: The main objectives of the Measure phase in Six Sigma are to identify and define key process metrics, gather accurate data, and establish a baseline for current process performance. This phase focuses on understanding the process and quantifying its variation to enable effective problem-solving. By collecting reliable data, teams can evaluate process capability and efficiency, leading to informed decision-making. According to a study conducted by International Six Sigma Institute, organizations implementing Six Sigma experienced an average improvement of 35% in process performance after completing the Measure phase.

Are there any best practices or tips for effectively executing the measure phase in Six Sigma projects?

Answer: Yes, there are several best practices and tips for effectively executing the measure phase in Six Sigma projects. Firstly, it is crucial to establish clear project goals and identify key process metrics before collecting data. It is also important to gather sufficient and representative data to ensure accurate analysis and decision-making. Additionally, utilizing statistical tools such as control charts, histograms, and process capability analysis can help assess the current process performance effectively. According to recent studies, organizations that follow these best practices during the measure phase have achieved a significant improvement in process efficiency, with a 25% reduction in defects and a 20% increase in customer satisfaction.

How does the measure phase contribute to process improvement in Six Sigma?

Answer: The Measure phase establishes a reliable baseline for the current process through data collection plans, process mapping, measurement system analysis and statistical summaries. Measures such as defect rates and capability indices can identify performance gaps. Root-cause analysis follows in Analyze, potential solutions are evaluated in Improve, and Control maintains the gains. These roles build on the problem and goals established in Define.

What are the key tools and techniques used in the measure phase?

Answer: In the Measure phase of Six Sigma, important tools and techniques used include process mapping, data collection, measurement system analysis (MSA), and statistical analysis. Process mapping helps to visually represent the current state of the process, identifying areas of improvement. Data collection allows for gathering relevant information about the process performance. MSA assesses whether the measurement system is sufficiently reliable and accurate for its intended use and identifies measurement effects that need improvement. Statistical analysis aids in analyzing collected data to identify trends, patterns, and potential sources of variation. According to a study conducted on Six Sigma implementation in manufacturing, utilizing these tools resulted in a significant reduction in defects by an average of 70% (source: Journal of Manufacturing Technology Management).

Variation between appraiser is also known as ...

Answer: Variation between appraisers is commonly called appraiser variation or reproducibility. A suitable R&R study uses repeated measurements of the same parts and characteristic under a defined procedure to estimate this effect. Investigating it can improve measurement consistency and reliability.

​In which phase of the Six Sigma, the sources of variation are identified?

Answer: Measure establishes reliable measurements and quantifies current variation. Analyze investigates and validates potential root causes using the data, process knowledge and suitable tools, including FMEA and process maps. Identifying and confirming causes should not be confused with measuring the baseline.

Sigma is a measure of ...

Answer: Sigma, σ, commonly denotes a standard deviation: a measure of spread. A sigma level is a different concept, expressing distance from a process mean to a specification limit in standard-deviation units under stated assumptions. Reliable measurement procedures and a clear process map support both kinds of assessment.

What is 6 sigma probability?

Answer: For a centered normal distribution, the probability of a value falling within six standard deviations on either side of the mean is approximately 99.99999980%. Conventional Six Sigma practice often uses a 1.5-standard-deviation shift when quoting about 3.4 defects per million opportunities. State which model, specification limits, tail convention and shift assumption you are using; these are different calculations.

​In DMAIC how the measurement focus varies in measure and control?

Answer: In the Measure phase of DMAIC (Define, Measure, Analyze, Improve, Control) in Six Sigma, the primary focus is on establishing robust measurement systems to accurately capture Critical-to-Quality (CTQ) parameters. The emphasis lies in identifying and validating key metrics essential to meeting customer requirements. As the project progresses into the Control phase, the measurement systems implemented during the Measure phase play a pivotal role in ensuring sustained process improvement, enabling continuous monitoring and control of CTQs to maintain the desired quality standards.

​

Plot processing times by using ...

Answer: Plot processing times in their collection order on a run chart or an appropriate control chart to examine change over time. A histogram or box plot answers a different question about the distribution. Define the process, measurement units and data collection procedure first; a value stream map can help connect the timing measures to process steps.

​Data in a time-ordered sequence will not be in measurements of?

Answer: A time-ordered plot preserves the sequence in which measurements were collected. A histogram groups values into intervals and does not retain that order. Use reliable measurement units and an appropriate collection plan so both the sequence and distribution can be interpreted meaningfully.

​

Variations six sigma?

Answer: In the Measure phase of Six Sigma's DMAIC methodology, a crucial aspect revolves around understanding and addressing variations. Variations, inherent in any process, necessitate a robust measurement system to accurately capture and quantify them. Therefore, the work in this phase focuses on establishing measurement systems that meet the precision and reliability needs essential for effective process analysis and improvement.

What MSA Six Sigma?

Answer: Measurement System Analysis evaluates whether the measurement process is suitable for its intended use. It examines bias, stability, linearity, repeatability, reproducibility and related sources of uncertainty. A SIPOC diagram describes the broader process; it does not, by itself, validate measurement accuracy or precision.

In which phase of the six sigma the sources of variation are identified?

Answer: Measure quantifies the baseline and checks the measurement system. Analyze investigates and validates the causes of observed process variation. Inputs such as materials, suppliers and operating practices can be potential causes, but their effects require evidence rather than assumption.

Recap for Measure Phase in Six Sigma

The Measure phase establishes trustworthy data and a baseline for process performance. Measurement system analysis helps distinguish measurement effects from actual process variation. These results guide the later investigation of root causes and support informed choices about improvements.

Successful implementation of the Measure phase has been demonstrated by numerous companies across various industries. Through careful measurement systems analysis and identification of variation sources, organizations have enhanced the quality of their products and services, leading to increased customer satisfaction and loyalty. Moreover, the insights gained from this phase have proven instrumental in optimizing supply chain operations, streamlining processes, and gaining a competitive edge in the market.
As you embark on your Six Sigma journey, consider delving deeper into the methodology's frameworks and applications. The International Six Sigma Institute offers a free Six Sigma Revealed book, providing valuable insights into the ways Six Sigma can be applied to drive success in company development. To learn more and access this valuable resource, visit https://www.sixsigma-institute.org/FreeSixSigmaBook.



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