Imagine that youíre a detective conducting a murder investigation. You will need to examine every bit of evidence to make sure you havenít overlooked clues to the murderer's identity. Certainly, if you find the butler standing over the corpse with a smoking gun in his hand, you can cut short the scope of your investigation. However, most murderers donít remain at their victimís side, waiting to be caught.
Now consider that youíve been assigned to the case of a serial killer. How would this investigation compare with the first? The high and grisly cost exacted by a serial killer heightens the urgency; you must solve this case before the killer strikes again. On the other hand, because the serial killer has murdered more than once, the larger pool of evidence works to your benefit, increasing the chances of finding telling clues.
When investigating an isolated murder, you might overlook a relevant clue. However, when probing a series of murders, patterns and commonalities that can indicate the killerís identity may become easier to spot.
So it is with the causes of errors. When you (or those who work for you) make a single error, with some labor, you can often discover the major causes with a thorough examination and analysis of the circumstances that led up to it. In many cases, applying the insights you achieve as a result of this analysis will allow you to correct the error appropriately and efficiently and perhaps even prevent future errors of a similar nature.
But, when you analyze several errors at once, you may discover patterns of error-making with promising clues to help you identify overlooked yet potent causes. And this insight will prove even more helpful in preventing future errors. By attacking the contributory causes of past errors, you significantly enhance your efforts to eliminate similar errors in the future.