The House of Lean Six Sigma – Room 2

In Part 1 of this series, we reviewed the foundational concepts of Allergan’s visualization of The House of Lean Six Sigma, covering both the Foundation and Roof of their house diagram.

In Part 2, we jumped into Room 1, where a problem and its cause are known. This room represents a ripe opportunity for immediate application of the Improve stage of the DMAIC (Define, Measure, Analyze, Improve, Control) methodology. 

In this installment, we enter Room 2. When a problem is known, but the cause is unknown, the Analyze phase of the Lean Six Sigma methodology takes precedence. Here, the team systematically investigates the situation, guided by data collected during the Measure phase. The goal is to understand the underlying issues that led to the observed problem and to determine the most impactful areas to target for improvement.

DMAIC – Define, Measure, Analyze, Improve, and Control

DMAIC is the more well-known and most-used Lean Six Sigma project method. DMAIC focuses on improving an existing process by incorporating the following phases:

  • Define: Define the problem, output to be improved, customers, and process associated with the problem.
  • Measure: Collect data from the process to establish a baseline for the improvements.
  • Analyze: Analyze the data to find the root causes of defects.
  • Improve: Develop, test, and implement solutions to improve the process.
  • Control: Implement process controls to sustain the improvements.

Room 2 Tools

Fishbone Diagrams

Also known as Ishikawa or Cause and Effect diagrams, Fishbone Diagrams are graphical tools used in Lean Six Sigma to identify and visually display potential causes of a problem. The diagram resembles a fish’s skeleton, with the main problem (effect) represented as the fish’s head and the possible causes grouped into categories along the bones, facilitating root cause analysis.


KTA stands for Knowledge Transfer Assessment, an essential part of the Lean Six Sigma methodology. It assesses knowledge transfer between different project phases and between other individuals or teams involved. The goal is to ensure that all key insights, learnings, and decisions are communicated effectively and understood by all stakeholders, supporting continuous improvement and the project’s long-term success.


Design of Experiments (DOE) is a systematic method used in the Improve phase of Lean Six Sigma. It helps to determine the relationship between factors affecting a process and the output of that process. It identifies vital interactions and process variables that impact performance through controlled experiments, providing valuable insights for optimizing the process.

Hypothesis Testing

Hypothesis Testing is a statistical method used in the Analyze phase of Lean Six Sigma to make inferences or decisions about population parameters based on sample data. It involves formulating a null hypothesis (the status quo) and an alternative hypothesis (the claim to be tested), and then using statistical analysis to determine which hypothesis is supported by the data.

Regression Analysis

Regression Analysis is a statistical technique used in Lean Six Sigma to understand the relationship between a dependent variable and one or more independent variables. By fitting a mathematical model to observed data, it can identify key predictors, quantify their impact, and forecast future values of the dependent variable. This can provide valuable insights for process improvement and decision-making.


While these tools are an integral part of a Six Sigma program, they can also be implemented as standalone quality improvement actions or as part of other process improvement initiatives. Return for future articles in this series to learn more about the other tools that support the House of Lean Six Sigma.

Process improvement is a way of life at Thurman Co.

In addition to an in-house culture that thrives on ownership and responsibility throughout our team, we help businesses manage projects to significantly impact their success and growth, which often includes analyzing and improving processes.

When you’re ready to put your project in the hands of a trusted professional organization, contact us to learn more about working together.

Leave a Comment

Your email address will not be published. Required fields are marked *

Discover more from Thurman Co

Subscribe now to keep reading and get access to the full archive.

Continue reading