Cpk vs. Sigma Level: What’s the Difference?

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What is Cpk? Cpk is short for Capability Index. It is a measurement of the capability of a process to deliver output that is within the specification limits of a process. The Benefits of Cpk With Cpk, you are able to determine how closely a process can meet overall specifications in its ability to produce […]

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Understanding Process Sigma Level

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Six Sigma is a data-driven approach to quality, aimed at reducing variation and the associated defects, wastes and risks in any process. This article explores the basics of Six Sigma process quality – definition and measurement. In a set of data, mean (μ) and standard deviation (σ) are defined as: μ = x1 + x2 […]

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Sigma Performance Levels – One to Six Sigma

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When learning about Six Sigma, it may help to consider these charts, which detail how sigma level relates to defects per million opportunities (DPMO), and some real-world examples. Sigma Performance Table Sigma Performance Levels – One to Six Sigma Sigma Level Defects (or Errors) Per Million Opportunities (DPMO) Yield (or Produced or Delivered) Correctly (%) […]

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Should You Calculate Your Process Sigma?

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Practitioners must learn when and how to calculate the sigma level of a process. Many people hear about the Six Sigma quality methodology and immediately want to calculate their own process sigma to determine how close (or far) they are from six sigma. My immediate response to them is twofold: Are you currently measuring your […]

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A Step-by-Step Guide: How to Calculate Process Sigma

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Consider a power company for illustration purposes: A power company measures their performance in uptime of available power to their grid. Here is the five-step process to calculate your process sigma. Step 1: Define Your Opportunities An opportunity is the lowest defect noticeable by a customer. This definition, of course, is debatable within the Six Sigma […]

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Customer CTQs – Defining Defect, Unit and Opportunity

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In order for any process capability to accurately be calculated, one must properly define and quantify the process defect, unit and opportunity of a customer CTQ. This article defines the three terms, as well as provides examples.

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A Method for Aligning the Six Sigma Performance Metric

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Some Six Sigma practitioners are concerned about the current method used to calculate Z-scores and express process capability. A proposed modification, based on Berryman’s scorecard, may fill the need for a more intuitive and business savvy metric.

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Finding the Sigma Level of Customer Complaints

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In the beginning of a deployment, many companies set a goal of 3.4 defects per million opportunities (DPMO) using Six Sigma quality concepts in production, and later extend this concept to other operational areas. Fewer companies, however, have extended Six Sigma from a manufacturing application to manage customer satisfaction or customer complaints. But it is […]

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Zero Defects: What Does It Achieve? What Does It Mean?

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The definition for Six Sigma was clear from the beginning – 3.4 defects per million opportunities (DPMO), allowing for a 1.5-sigma process shift. But the definition for zero defects is not so clear. Perhaps zero defects refers to the domain beyond 3.4 DPMO. Or perhaps it refers to designing defects out of the process or product, […]

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Using Weighted-DPMO to Calculate an Overall Sigma Level

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An organization is always successful in its journey towards business excellence if it has specific goals for each of its critical processes. Various quality management programs adopted and implemented by such an organization can streamline the activities towards the ultimate goal of business excellence. When the quality improvement program is Six Sigma, the goal for […]

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Sigma to DPMO to Yield to Cpk Table

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Use this table to go between and convert Sigma to DPMO to Yield to Cpk.

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Yield to Sigma Conversion Table

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When you know your process yield (percentage of a process that is free of defects), you can use this yield to sigma conversion table to easily determine your process sigma level, as well as your process defects per million opportunities.

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