Statistical process control sounds like a complex term, and indeed it can become rather complicated once you get into it. But for beginners, it can be defined quite simply: Statistical process control refers to a group of strategies for monitoring processes using methods originally set forth in the field of statistics. While it is typically used in manufacturing and other types of business, it can be applied to virtually any fairly rigid process. It can even be applied to everyday processes in people’s lives.

Controlling The Human Element

There are many reasons why statistical analysis is useful for evaluating processes, but the biggest factor in favor of statistical process control is its objectivity. While other evaluation methods involve human judgment and hence are subject to flaws of subjectivity and simple human error, statistical process control looks at the actual results with no evaluation and no human judgment.

The underlying assumption of statistical process control is that by quantifying elements of processes and examining them in raw numbers, the truth about where the processes work and don’t work can be reached. But of course, it’s important to keep in mind that not everything can be measured statistically. For instance, statistical process control can be used to make sure every item that comes off an assembly line falls within the range of certain specs, but what it cannot so easily do is quantify customer satisfaction with the items. Subjective human reactions to things are inherently unreliable as data, especially since people often don’t know exactly why they do or do not like something.

But with that being said, there are ways that statistical process control can be applied to human reactions to things—namely, by taking a large sample size. So, for example, if you poll five people about why they do or do not like a product, you’re liable to get a range of answers, some unexpected, and you probably won’t get any actionable information out of it. But if you analyze the behavior of 5,000 people with regard to a product, this gives you very clear data about human tendencies.

Protecting Against Human Error

While human reactions to a problem don’t necessarily apply directly to the process under analysis, what they can do is point toward parts of the process that could be improved. The failure of a product can stem from a variety of sources. Sometimes it boils down to poor planning or design, sometimes it relates to bad craftsmanship or shoddy materials, and sometimes it’s from lack of quality control. Getting a sense of the human response to a product should point to which of these is most relevant.

Setting aside how people respond to products, the essential benefit of statistical process control is that it is useful in virtually any type of manufacturing that follows a fairly rigid process. There can be some difficulty in pinpointing where in the process to take the statistical data, but once this is set, it becomes an incredibly efficient way to locate points in the process that have deteriorated or where things could be improved. If the data is read correctly, then human judgment doesn’t even enter into it.