Categories of errors
There are two ways of looking at human factors that lead to problems and accidents:
- You can see the human error as the cause of a mishap. In this case
"human error," under whatever label—loss of situation awareness, procedural violation, regulatory shortfalls, managerial deficiencies is the conclusion of your investigation.
- You can see the human error as the symptom of deeper trouble. In this case, human error is the starting point for your investigation. You
will probe how human error is systematically connected to features
of people's tools, tasks, and operational / organizational environment.
The first is called the human approach, and the second as the system approach.
To explain failure using the human approach, you would seek failure and find people's inaccurate assessments, wrong decisions or bad judgments.
To explain failure using the system approach, you are not trying to find where people went wrong. Instead, find how people's assessments and actions made sense at the time, given the circumstances that surrounded them.
For example, Donald Berwick of the Institute for Healthcare Improvement (IHI) argues that improving patient safety requires changes in the design of systems:
...We are human, and humans err. Despite outrage, despite grief, despite experience, despite our best efforts, despite our deepest wishes, we are born fallible and will remain so. Being careful helps, but it brings us nowhere near perfection... The remedy is in changing systems of work. The remedy is in design. The goal should be extreme safety. I believe we should be as safe in our hospitals as we are in our homes. But we cannot reach that goal through exhortation, censure, outrage, and shame. We can reach it only by a commitment to change, so that normal, human errors can be made irrelevant to the outcome, continually found, and skillfully mitigated.
Donald M Berwick. Not again! BMJ 2001
Removing mistakes from the system
A great way to find (and correct) the various ways failure happens after the fact, is searching for the root cause without blaming the people. This is often called "blameless post-mortems", and Etsy Code as Craft blog post expands on the concept. People at Etsy presented and wrote more about it on other forums and blogs.
To prevent mistakes in the first place, some culture traits are a must. Procedures and various artifacts created in the system must test that using them by humans is very clear and self-explanatory. Often those who create are not those who consume, leading to a disconnect and lack of clarity. The system is then not safe to operate since the only person who knows all the assumptions is the one who created it (and no one else).
Effective control measures
Put in place effective control measures to stop the process when an error occurs. This is mistake-proofing. Effective control measures are design changes that prevent or stop processes from continuing when an error has occurred by introducing a process failure
In 1896, Sakichi Toyoda invented Japan’s first power loom called “the Toyoda Steam power loom.” This development increased productivity by twenty times, and the quality of the textiles improved and caused a revolution in the textile industry in Japan. But here’s the subtle but very important discovery and principle:
when the needle broke, the machine stopped
Sakichi Toyoda created an innovation to the Loom that would later become one of the pillars in the Toyota Production System (Lean). That pillar we now call Jidoka, sometimes called “smart automation with a human touch” or “autonomation.”
In large part, Andon (stop at first defect) and Poka-Yoke (mistake proofing) are later developments that find their influence from the Loom.
Removing Single-Point Weaknesses
The term single-point weakness refers to the creation of redundancies in the system as an approach to improving system reliability. Redundancy is created by increasing the number of systems or individuals involved in the process. Having more backup systems or more checks (double, triple, or more) increases the probability that the process will proceed correctly.
One great example for this is the "four-eyes principle," which means that "all business decisions and transactions need approval from the CEO and CFO. Since the CFO is not reporting to the CEO, there is an independent controlling mechanism in place".
Make Hazards Obvious
If hazards are made obvious, or impossible to reach, humans cannot create mistakes. For example, color-coding is a common approach to making mistakes more obvious. Or if you think of various computer sockets that can only be inserted one way and not the other, etc.
Some great books are talking about the subject, and it would not be a good answer without mentioning them: