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Part V – Understanding the voice of the random process

If, when playing dice, we score 1 point three times in a row, we probably won’t ask about the cause of such an event. We understand that we are dealing with a random process, so the question about the cause of the event is pointless. However, if we have low sales for the third month in a row, we start to believe that there must be some reason for this. In fact, it’s half the problem if we do look for the cause. It is much worse when we start looking for a guilty person. The former leads to an unnecessary loss of manpower and resources, while the latter — to deep human demotivation.

And yet, the sales process is to a large extent a random one, so the question about the reason for drops or growths may just be as unfounded as in the case of a game of dice. However, the sales process can also be disturbed by external factors, and in this case, the question “What happened?” does actually make sense. The thing is to distinguish between a random situation, in which the cause does not exist, from a non-random situation, when the cause is worth looking for. This requires some general knowledge of random processes and a specialized knowledge of the Shewhart control chart method. And this is what the reader will find in Part V.