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Total Quality Management - CII Institute of Logistics

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<strong>Total</strong> <strong>Quality</strong> <strong>Management</strong><br />

5.2 What is Six Sigma?<br />

Six Sigma is a statistical measure that says that in a well-managed process be it<br />

manufacturing or service, you encounter only 3.4 Defects Per Million Opportunities<br />

(DPMO). In the parlance <strong>of</strong> Six Sigma, any thing that inhibits the attainment <strong>of</strong> customer<br />

expectation and satisfaction is a defect. First, we compute the ratio between the actual<br />

defects and the total number <strong>of</strong> opportunities for the organization to make mistakes from<br />

the customers’ angle. If this ratio is multiplied by one million, you get the Sigma level<br />

achieved by your organization. This level may be far from Six Sigma. For example, it<br />

may correspond to 2 Sigma, 3 Sigma or 3.5 Sigma. In the context <strong>of</strong> Six Sigma, we are<br />

99.99966% confident that the product or service delivered by us is defect free. Only<br />

0.00034% <strong>of</strong> the times the product or service delivered are defect prone. When multiplied<br />

by one million, this becomes 3.4 DPMO.<br />

Six Sigma measure is based on the bell shaped normal distribution. Normal distribution is<br />

the foundation stone upon which the entire statistical inference is built. The following<br />

diagram succinctly captures the meaning <strong>of</strong> Six Sigma<br />

<strong>CII</strong> <strong>Institute</strong> <strong>of</strong> <strong>Logistics</strong> 92<br />

Website: www.ciilogistics.com

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