DPMO and Process Sigma (Sigma Level): Scenario

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The page below is a sample from the LabCE course Basics of Lean and Six Sigma for the Laboratory. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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DPMO and Process Sigma (Sigma Level): Scenario

A laboratory reports 1000 ED stat results in a month (Product).
10% or 100 results are not reported within the specified time (Defects).
The number of Opportunities for defects is 3, representing the three phases of testing (preanalytical, analytical, and post-analytical phases).
Once the number of products, defects, and opportunities are known, both DPMO and Sigma level can be calculated.
  1. Defects per opportunity (DPO)= Defect/(Product x Opportunities). Using the data presented in the scenario,

    DPO= 100/(1000 X 3) or 0.033333

  2. Defects per million opportunities (DPMO) Six Sigma is determined by evaluating the DPMO, Multiply the DPO by one million.
    DPMO= 0.33333 X 106 or 33,333

  3. Process Sigma Once you have determined the DPMO, you can now use a Six Sigma table to find the process sigma. You will look for the number closest to 33,333 under defects per 1,000,000. In this case, the process sigma is ~ 3.3.
A Six Sigma conversion table is available at: http://www.six-sigma-material.com/Tables.html. Accessed February 21, 2024.