When initiating process improvement the question often arises which to pursue first – Lean, Agile, Six Sigma or a combination of these tools.

There have been case studies surrounding the order of choice – or whether Lean and Six Sigma complement each other at all. Many Six Sigma experts have spent significant time living and dying Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) and its outgrowths – DFSS (Design for Six Sigma) and DMADV (Design, Measure, Analyze, Design, Verify). Consequently, it appears most users are biased in favor of Six Sigma.

Following are three case studies that involved organizations implementing and expanding Six Sigma. Black Belts, Green Belts and Champions were trained within the organizations and most staff received a four-hour Six Sigma orientation.

The Three Organizations

The organizations studied were in the following industries:

  1. An information technology (IT) organization of a large educational supplier
  2. A medium-sized financial specialty company
  3. A 100+ person division of a multi-national communications vendor

All of the organizations had made significant inroads into Six Sigma (DMAIC) before they ventured into Lean. Each was introduced to Lean via training and consulting. After three months of project work the companies held a formal status review. The results were significantly better than the average beginning projects. All three had results more typical of a practiced, stable implementation than results typical of initial process improvement. Especially noticeable was the difference in the quantitative-based nature of the Lean approaches. In most early status reviews of Lean results, companies do not pay much attention to measures. In all three examples, however, many product, process and project measures were collected and analyzed. The cases below show some key measures common to all three groups. The measures sampled and analyzed were:

  • Schedule compliance: The comparison of schedule – planned versus actual
  • Percent features delivered: The percentage of features delivered according to plan
  • Effort compliance: The comparison of effort – planned versus actual
  • Budget compliance: The comparison of budget – planned versus actual
  • Total defects: The total number of defects injected during the process
  • Released defects: The number of defects found by the customer/user
  • Total failure modes and effects analysis relative priority number (FMEA RPN): A hash total (in this case the number has no particular value) of the summary of RPN values

Case 1 Analysis

The following data results (normalized) were posted for Case 1:

Measure Old Baseline After Lean Implementation
Schedule compliance 131% 104%
Percent features delivered 82% 98%
Effort compliance 138% 105%
Budget compliance 142% 106%
Total defects 2,029 1,011
Released defects 202 63
Total FMEA RPN 3,113 1,021

Case 2 Analysis

The following data results (normalized) were posted for Case 2:

Measure Old Baseline After Lean Implementation
Schedule compliance 141% 107%
Percent features delivered 80% 98%
Effort compliance 142% 107%
Budget compliance 147% 108%
Total defects 3,114 1,121
Released defects 282 93
Total FMEA RPN 3,941 1,102

Case 3 Analysis

The following data results (normalized) were posted for Case 3:

Measure Old Baseline After Lean Implementation
Schedule compliance 152% 105%
Percent features delivered 78% 97%
Effort compliance 141% 109%
Budget compliance 142% 108%
Total defects 2,629 1,205
Released defects 384 85
Total FMEA RPN 4,613 1,190

The above results are unexpected for early Lean implementations. Upon further investigation all stakeholders agreed that the Six Sigma tools and, more importantly, the Six Sigma cultural “mindset” had contributed greatly to the results. Also documented were such shared characteristics as:

  • All processes and procedures contained measurements, root cause analysis and continuous improvement follow-up
  • All organizational results exceeded the data published in the Lean training and embedded case studies
  • All levels of management and staff used the measurements on a daily basis

More interestingly, all three case studies involved organizations whose Six Sigma training and focus had been strictly DMAIC. All three believe that their Lean results would have been even better if their Six Sigma training had included the concepts in DFSS, with more focus on understanding requirements and performance drivers versus DMAIC “fix and improve” approaches.


These three cases are solid examples of the horsepower gain for Lean and Agile driven by an early Six Sigma base and mindset. More importantly, they demonstrate the synergy of Lean and Six Sigma. Too often, they are discussed as rival methodologies rather than approaches that benefit each other. Six Sigma experts should be proud of the gains they drove – and continue to drive – via the tools and cultures of quality and process.

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