Six Sigma

Six Sigma is a business management strategy that strives to increase the quality of output of a firm by minimizing defects and maximizing certain financial variables. Sig Sigma processes, by definition, are expected to ensure that 99.99966% of the manufacturing line is free from defects - it is essentially guaranteeing perfection amongst the products that the firm manufactures. A Six Sigma defect is any deviation from customer specification. The term ‘sigma' itself denotes the process standard deviation of the product being manufactured. There are different levels of sigma that attempt to guarantee different levels of defect-free product. For the purposes of Six Sigma, the ‘Cp index' is calculated by finding the difference between the ‘upper specification limit (USL)' and the ‘lower specification limit (LSL),' and dividing this value by six times the project sigma. These two limits, USL and LSL, are defined as the limits to which the item being produced is specified - different USL and LSL's exist for different items being manufactured depending on what the company is attempting to achieve. A Six Sigma project would have a Cp index greater than 1, indicating that the limits of specification would be greater than six times the standard deviation and establishing the aforementioned 99.99966% defect-free production quality. Once implemented, companies see an increase in profitability and an increase in customer satisfaction. It is also advantageous in that it attempts to solve the problem of the defective product in a proactive way - the firm with Six Sigma can prevent the defective product and the negative costs associated with it rather than having to fix the defect once the product is on shelves.