In our experience, it is rare to be able to determine that the actual cause of a product failure is due to a single reason. Often, the actual causes are a result of factors external to the product and not due to a defect with the product itself.
It is easily to fall into the trap of attributing the cause of a product defect to the most obvious observation. Therefore, it is critical when investigating problems to use as broad and extensive methodology, as is practical, in eliminating the causes of the problems.
At CETEC, the guidance we use in assessing, solving and managing technical problems is one based upon established risk management techniques and processes. This involves:
- Context: First establishing the context of the problem to ensure that you understand the scope and parameters surrounding the problem. Setting the scope and boundaries identifies any studies needed and their scope, objectives and the resources required to solve the problem. It is important at this stage to develop the evaluation criteria, which may be further developed and refined subsequently as particular causes are identified.
- Identification: Identifying all possible or potential causes of what has gone wrong and how it could have happen. At this stage, it is important to identify and include all causes whether or not they are obvious or not. Comprehensive identification using a well-structured systematic process is critical, because a potential cause of the defect not identified at this stage could be excluded from further analysis.
- Analysis: The next stage is to analyse the source and likelihood of each cause. The objective of the analysis is to eliminate the unlikely causes and to separate the minor possible causes from the probable major causes. A preliminary analysis can be carried out at this stage to exclude minor potential causes where limited funds are available.
- Evaluation: The evaluation process involves comparing the probable causes found during the analysis process with the previously established end evaluation criteria. The output of this stage is to prioritize the list of causes for further action, including modelling and testing.
- Test & Review: This stage involves identifying the range of testing options available, assessing those options, preparing testing programs and implementing them. It is important at this stage to monitor and review the results against the establish evaluation criteria. Ongoing review is essential to ensure that the criteria remain relevant. The process is iterative and may be repeated many times with additional or modified cause evaluation criteria, leading to a process of continual review.