gen-define-six-sigma-and-defect-rates-and-give-one-short-worked-1251

Define Six Sigma and defect rates and give one short worked example.

# Six Sigma Definition **Six Sigma** is a quality management methodology that aims to reduce process variation and defects to extremely low levels. The term "sigma" (σ) refers to standard deviation from the mean in a normal distribution. ## Defect Rates by Sigma Level | Sigma Level | Defects Per Million Opportunities (DPMO) | Yield % | |-------------|------------------------------------------|---------| | 3σ | 66,807 | 93.3% | | 4σ | 6,210 | 99.4% | | 5σ | 233 | 99.98% | | **6σ** | **3.4** | **99.9997%** | **Six Sigma = 3.4 defects per million opportunities** --- ## Worked Example **Scenario:** A call center receives 50,000 calls per month. Each call has 4 opportunities for defects (wrong information, long hold time, rude service, unresolved issue). **Current performance:** 500 total defects observed **Calculate the Sigma Level:** 1. **Total opportunities** = 50,000 calls × 4 = 200,000 2. **DPMO** = (500 defects ÷ 200,000) × 1,000,000 = **2,500 DPMO** 3. **Current sigma level** ≈ **4.5σ** (between 4σ and 5σ) **To reach Six Sigma:** Defects must reduce from 500 to fewer than 1 per month (0.68 to be exact). This demonstrates why Six Sigma represents world-class quality performance.