Construction of tightened-normal-tightened schemes indexed through Six Sigma quality levels

'Six Sigma is a tool used to convert management problem into a statistical problem and to find a statistical solution then it converts into a management solution'. Six Sigma is a set of practices originally developed by Motorola to systematically improve processes by eliminating non-conformities. The term Six Sigma refers to the ability of highly capable processes to produce outputs within specification. In particular processes that operate with Six Sigma quality produce 3.4 or less number of non-conformities per one million opportunities (dpmo). This Six Sigma concept can be applied in the construction of sampling plans also. In this paper a new procedure for the construction and selection of tightened-normal-tightened scheme [TNT-(n; c1, c2)] with c1 = 0 and c2 = 1 indexed through Six Sigma quality level-1 (SSQL-1) and Six Sigma quality level-2 (SSQL-2) are presented. Tables are also constructed and presented for the easy selection of the schemes. These schemes can be used by the companies which practice Six Sigma initiatives in their organisations.