Allows for screening of important factors and main effects, but may confound (mix up) interactions.

Response Surface Methodology (RSM): Used after identifying critical factors to model and optimize the response, often using quadratic models.

Main Effect: The average change in the response caused by changing a factor from its low level to its high level, averaged across all levels of other factors.

Interaction: Occurs when the effect of one factor on the response depends on the level of another factor. Interactions are crucial to discover as they can lead to unexpected results if ignored.

Example: Factor A improves yield at low temperature, but decreases yield at high temperature.

Advantages of DOE:

Efficiently identifies the most influential factors among many.
Uncovers interactions between factors that cannot be found by changing one factor at a time.
Optimizes process settings to achieve desired performance (e.g., maximize yield, minimize defects).
Reduces the number of experimental runs compared to OFAT.

Disadvantage of OFAT (One-Factor-At-a-Time):

Inefficient: Requires many more runs to cover the same factor space.
Cannot detect interactions: Fails to identify how factors influence each other, leading to suboptimal solutions.

16. Additional Brainstorming & Process Improvement Tools

A variety of tools support idea generation, problem analysis, and organization within Six Sigma projects.

Activity Network Diagram (Arrow Diagram/Precedence Diagram): A project management tool that graphically represents the sequence of activities in a project, showing dependencies and critical paths.
- Use: To plan, schedule, and monitor complex projects, especially in the Improve phase.
Affinity Diagram (KJ Method): A brainstorming tool used to organize a large number of ideas or issues into natural groupings based on their relationships.
- Use: To synthesize qualitative data, identify common themes, and prioritize problems or solutions.
Interrelationship Diagram (Relations Diagram): Shows cause-and-effect relationships between various factors or issues. It helps identify the most influential drivers and outcomes.
- Use: To understand complex, intertwined problems and identify root causes in the Analyze phase.
Force Field Analysis: A technique for identifying the driving forces (factors pushing towards change) and restraining forces (factors resisting change) related to a problem or proposed solution.
- Use: To analyze the feasibility of implementing solutions and to develop strategies for overcoming resistance.
RACI Chart: A matrix that clarifies roles and responsibilities for tasks or deliverables.
- R - Responsible: The person who does the work.
- A - Accountable: The person ultimately answerable for the correct and thorough completion of the deliverable (only one per task).
- C - Consulted: People whose opinions are sought.
- I - Informed: People who are kept up-to-date on progress.
- Use: To ensure clear communication and avoid confusion in team projects.
Nominal Group Technique (NGT): A structured method for brainstorming that encourages participation from all members and prioritizes ideas through