An error-tolerant design (or human-error-tolerant design
) is one that does not unduly penalize user or
human error
Human error is an action that has been done but that was "not intended by the actor; not desired by a set of rules or an external observer; or that led the task or system outside its acceptable limits".Senders, J.W. and Moray, N.P. (1991) Human Er ...
s. It is the human equivalent of
fault tolerant design that allows equipment to continue functioning in the presence of hardware faults, such as a "limp-in" mode for an
automobile
A car, or an automobile, is a motor vehicle with wheels. Most definitions of cars state that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, peopl ...
electronics unit that would be employed if something like the
oxygen sensor
An oxygen sensor is an electronic component that detects the concentration of oxygen molecules in the air or a gas matrix such as in a combustion engine exhaust gas.
For automotive applications, an oxygen sensor is referred to as a lambda senso ...
failed.
Use of behavior shaping constraints to prevent errors
Use of forcing functions or
behavior-shaping constraints is one technique in error-tolerant design. An example is the
interlock or lockout of reverse in the
transmission of a moving car. This prevents errors, and prevention of errors is the most effective technique in error-tolerant design. The practice is known as
poka-yoke
is any mechanism in a process that helps an equipment operator to avoid mistakes and defects by preventing, correcting, or drawing attention to human errors as they occur. It is a Japanese term that means "mistake-proofing" or "error prevention", ...
in Japan where it was introduced by
Shigeo Shingo
was a Japanese industrial engineer who was considered as the world’s leading expert on manufacturing practices and the Toyota Production System.
Life and work
After having worked as a technician specializing in fusions at the Taiwanese railw ...
as part of the
Toyota Production System
The Toyota Production System (TPS) is an integrated socio-technical system, developed by Toyota, that comprises its management philosophy and practices. The TPS is a management system that organizes manufacturing and logistics for the automobile ...
.
Mitigation of the effects of errors
The next most effective technique in error-tolerant design is the mitigation or limitation of the effects of errors after they have been made. An example is a checking or confirmation function such as an
"Are you sure" dialog box with the harmless option preselected in computer
software
Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications.
The history of software is closely tied to the development of digital comput ...
for an action that could have severe consequences if made in error, such as deleting or overwriting files (although the consequence of inadvertent file deletion has been reduced from the
DOS
DOS (, ) is a family of disk-based operating systems for IBM PC compatible computers. The DOS family primarily consists of IBM PC DOS and a rebranded version, Microsoft's MS-DOS, both of which were introduced in 1981. Later compatible syste ...
days by a concept like the
trash can
A waste container, also known as a dustbin, rubbish bin, trash can, garbage can, wastepaper basket, and wastebasket, among other names, is a type of container intended to store waste that is usually made out of metal or plastic. The words "r ...
in
Mac OS
Mac operating systems were developed by Apple Inc. in a succession of two major series.
In 1984, Apple debuted the operating system that is now known as the classic Mac OS with its release of the original Macintosh System Software. The system ...
, which has been introduced in most
GUI interfaces). Adding too great a mitigating factor in some circumstances can become a hindrance, where the confirmation becomes mechanical this may become detrimental - for example, if a prompt is asked for every file in a batch delete, one may be tempted to simply agree to each prompt, even if a file is deleted accidentally.
Another example is
Google
Google LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...
's use of
spell checking on searches performed through their search engine. The spell checking minimises the problems caused by incorrect spelling by not only highlighting the error to the user, but by also providing a link to search using the correct spelling instead. Searches like this are commonly performed using a combination of
edit distance
In computational linguistics and computer science, edit distance is a string metric, i.e. a way of quantifying how dissimilar two String (computing), strings (e.g., words) are to one another, that is measured by counting the minimum number of opera ...
,
soundex
Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English. The goal is for homophones to be encoded to the same representation so that they can be matched despite minor differences in spelling. The algorithm mainly enc ...
, and
metaphone
Metaphone is a phonetic algorithm, published by Lawrence Philips in 1990, for indexing words by their English pronunciation. It fundamentally improves on the Soundex algorithm by using information about variations and inconsistencies in English s ...
calculations.
See also
*
Human factors
Ergonomics, also known as human factors or human factors engineering (HFE), is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Primary goals of human factors eng ...
*
Human reliability
In the field of human factors and ergonomics, human reliability (also known as human performance or HU) is the probability that a human performs a task to a sufficient standard. Reliability of humans can be affected by many factors such as age, ...
*
Murphy's law
Murphy's law is an adage or epigram that is typically stated as: "Anything that can go wrong will go wrong."
Though similar statements and concepts have been made over the course of history, the law itself was coined by, and named after, Americ ...
References
* To Err is Human, Chapter Five in
Donald A. Norman (2002),
The Design of Everyday Things
''The Design of Everyday Things'' is a best-selling book by cognitive scientist and usability engineer Donald Norman. Originally published in 1988 with the title ''The Psychology of Everyday Things'', it is often referred to by the initialisms ' ...
.
External links
Modeling Human Error for Experimentation, Training, and Error-tolerant DesignMaking reliable distributed systems in the presence of software errors
{{Design
Error
Fault-tolerant computer systems
Computer errors
Toyota Production System
User interface techniques
Reliability engineering