Updated on April 4, 2025

Cause-effect chain analysis

Cause – effect chain analysis (CECA) is an analytical tool that identifies the key disadvantages of the engineering system. This is accomplished by building cause-effect chains of disadvantages that link the initial disadvantage with its fundamental causes.

Overview

Regardless of whether you are dealing with a device or a process, it is essential to conduct a function-cost analysis and (optionally) a flow analysis before performing CECA. Function and cost disadvantages, as well as flow disadvantages (if identified) are the fundamental building blocks of CECA, and all of them should be considered in the analysis.

The primary outcome of CECA is a list of key disadvantages.

Cause-effect chain analysis can be performed for both devices and processes.

Performing CECA

Procedure

Building CECA begins with the initial disadvantage formulated by inverting the goal of the project. Next, we ask the question why? to understand what directly causes it. Disadvantages identified in earlier analyses are typically used at the beginning of the chains. However, they can also appear in the middle or at the end of the chain, as they are not always the direct cause of the initial disadvantage.

As the chain progresses downward, more disadvantages are revealed, with each subsequent one serving as the cause of the previous one. Disadvantages that lie between the initial disadvantages and the key disadvantages are referred to as intermediate disadvantages.

The final step of the analysis is to designate certain disadvantages as key disadvantages, and it is up to you to decide which ones to select. Usually, they can be found the end of the chains, however it is not uncommon to assign the status of key disadvantage to some intermediate disadvantages.

Starting and ending the analysis

The key point in CECA is to determine where to start and when to stop the chain.

As mentioned, the starting point for the analysis is always the initial disadvantage. As for stopping the analysis, there are two main recommendations:

  1. If the disadvantage is caused by a natural phenomenon (physical, chemical, biological, geometric, etc.), asking questions why? further is meaningless. For example, if it is needed to answer the question Why does water consist of hydrogen and oxygen molecules?, the answer is always That is just the way it is.
  2. If the cause of the disadvantage is beyond your control and influence of this project. It may be caused by administrative or legislative restrictions that cannot be circumvented (e.g., radiation level is limited by the law), project constraints may prevent from solving the problem that lies behind the disadvantage (e.g., redesigning the component associated with the disadvantage exceeds the project budget), or you may have no influence on the solution of the problem that is behind the disadvantage (e.g., a certain assembly cannot be redesigned since it is provided by an external supplier).

Sometimes, a chain cannot be completed because the cause of the disadvantage leads back to a previous one, creating what is known as a vicious circle.

AND and OR operators

If one disadvantage is caused by two or more disadvantages, it is necessary to use one of the operators that indicate the relationship between them:

  • operator AND is used if at least two causes have to occur simultaneously for a disadvantage to appear; removing one of them does automatically remove the other;
  • operator OR is used if one disadvantage is caused by several factors that are independent of each other; removing one of them does not remove any other automatically.

Recommendations

The technique used for building cause-effect chains involves multiple asking the question why? It is recommended that at least 5 levels down from the initial disadvantage be analyzed, what means that the question why? should be asked at least five times (that is why this tool is sometimes called a method of 5 Whys).

It is recommended to complete the entire branch of the chain before starting the next one.

Note that CECA is composed of disadvantages only. Do not enter positive and advantageous effects into the chain.

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