Cause and Effect Chain Analysis

Cause and Effect Chain Analysis

• Cause-and-effect analysis generates hypotheses about the causes and effects of problems.
• A Cause & Effect Chain (CEC) analysis uses a diagram to systematically express hypotheses about why a problem exists or why a desired outcome isn't achieved.
• This method helps focus attention on the process where a problem occurs and allows for constructive use of facts to identify the root cause.
• It cannot replace empirical testing and doesn't definitively identify the single root cause, but explores possible causes.

Steps in Cause & Effect Chain Analysis

• Step 1: Define and negate the problem; list potential causes and categorize them.
• Step 2: Brainstorm likely causes and organize them into major categories or branches.
• Step 3: Create a list of potential causes, filling them in appropriate categories.
• Step 4: Keep asking "Why?" and "Why else?" for each cause, until underlying causes are identified.
• Step 5: Use collective judgment to evaluate the likelihood of various causes. Eliminate unlikely ones.
• Step 6: Repeat step 5, focusing on the most likely causes.
• Step 7: Validate the most likely root cause by testing the hypothesis. If initial findings are inaccurate, revisit potential causes.

Chains of Problems in an Engineering System

• The diagram illustrates how various problems (known and hidden) interconnect to form a chain within an engineering system, leading to the target problem.
• Different problems are identified across different levels to illustrate causation.

Example - Cause-Effect Chain

• Wrong diet leads to excessive salts in the blood, leading to high blood pressure, and eventually headache.
• This example highlights the causal relationship between steps.

Cause & Effect Chain Analysis - Example

• The chain describes how a light not turning on is due to a broken switch, broken light bulb, or a cracked socket.

Case Study - Procter & Gamble

• The coffee bag was developed to replace instant coffee and maintain convenience but had slow coffee extraction.
• The challenge is to lower the cost of the coffee bag.

Key Problems - Coffee Bag Example

• The analysis explores the high cost of the coffee bag, linking it to excessive coffee and low extraction rates.
• This is tied to the amount of Ca and Mg ions in the water.

Solutions - Coffee Bag Example

• Adding ionite particles to the coffee bag helps reduce the negative effects of Ca and Mg ions while maintaining flavor and chemical composition.

Exercises

•  The exercise section provides examples of specific problems to address using the CEC analysis technique, such as school children's shoulder pain, face masks clouding/obscuring spectacles, and EBB (presumably some kind of device) not switching on.