RPN Number

  The RPN or Risk Priority Number is a quantitative assessment of risk that is assigned to a process or product function as part of a failure modes & effects analysis.  Individuals or teams assign the RPN based on an established criteria measuring the severity of impact, frequency of occurrence and the likelihood of detection.

• Severity is an estimate of how severe the customer or end user will perceive the effect of a failure.
• Occurrence is another numerical estimate of the likelihood that the cause of a failure mode will occur.
• Detection is a numerical estimate of the effectiveness of the controls to prevent or detect the cause or failure mode before the failure occurs or reaches the customer.

  A common way to rate these categories is to establish your own specific criterion and attach a number based on a scale such as one to five or one to ten depending on what you choose.  An individual or a team would then use a template and insert their data based on analysis.
  To calculate the Risk Priority Number you can multiply the probability by the severity by the likelihood of the failure escaping detection.  The answer of these three numbers multiplied is your RPN number.  It should be noted that potential failures with a high probability of occurrence, a high degree of severity and a low chance of being detected would naturally have the most risk.  As such the RPN would be the highest. Once the RPN is established it is then ranked to see which Failure in the series would require some type of corrective action first. 

Click Here to Visit Lean Strategies International's Template Page.

Use this to complete the challenge.

Challenge:
  A local distribution company wants to calculate the risk priority number for 3 potential damages to their inventory at a local distribution center.  The team has assigned rankings of one to 5 for each of the three categories: probability of occurrence, severity of failure and probability of not being detected.  5 is the worst.  They choose three possible failures shown above.  The scores are also shown.  Which of these three options scored the highest RPN? 

• Place your answer in the comments below and share with us, what opportunities can you think of where someone might want to calculate a risk priority number?

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