Type I vs. Type II Error: Which one was committed by Toyota?
Tuesday, March 9th, 2010In the previous post, I related the Toyota issue of sticking accelerator to the type of costs incurred. When failure occurs after the product reaches the customer, the associated costs are regarded as External Failure costs. This goes much further upstream than just replacing the defective part or settling a liability issue. Many examples where given in the previous post as well.
Here, I would like to relate this to the type of error. In general, there are 4 scenarios:
- Your product or service is GOOD and your QC program let it PASS
- Your product or service is GOOD and your QC program REJECTED it
- Your product or Service is NO GOOD and your QC program let it PASS
- Your product or service is NO GOOD and your QC program REJECTED it
Now guess which scenario affected Toyota’s reputation and bottom line!
When QC lets a NO GOOD product go to the customer, that’s a serious type of error (Type II). This is often called “Consumer’s Risk” beacuase the customer is paying a price as well as Toyota (In this case, deaths resulted from failure). The impact of such error for Toyota, primarily because it deals with safety, is huge and most likely will last a long time.