An error-tolerant design (also: human-error-tolerant design
) is one that does not unduly penalize user or
human error
Human error refers to something having been done 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 ...
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 automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods.
The year 1886 is regarde ...
electronics unit that would be employed if something like the
oxygen sensor failed.
Use of behavior shaping constraints to prevent errors
Use of forcing functions or
behavior-shaping constraint
A behavior-shaping constraint, also sometimes referred to as a forcing function or poka-yoke, is a technique used in error-tolerant design to prevent the user from making common errors or mistakes. One example is the reverse lockout on the tra ...
s is one technique in error-tolerant design. An example is the
interlock
An interlock is a feature that makes the state of two mechanisms or functions mutually dependent. It may be used to prevent undesired states in a finite-state machine, and may consist of any electrical, electronic, or mechanical devices or system ...
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 a Japanese term that means "mistake-proofing" or "inadvertent error prevention". A poka-yoke is any mechanism in a process that helps an equipment operator avoid (''yokeru'') mistakes (''poka'') and defects by preventing, correcting, or drawing ...
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 m ...
.
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 is a set of computer programs and associated software documentation, documentation and data (computing), data. This is in contrast to Computer hardware, hardware, from which the system is built and which actually performs the work.
...
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 shorthand for the MS-DOS and IBM PC DOS family of operating systems.
DOS may also refer to:
Computing
* Data over signalling (DoS), multiplexing data onto a signalling channel
* Denial-of-service attack (DoS), an attack on a communicat ...
days by a concept like the
trash can in
Mac OS
Two major famlies of Mac operating systems were developed by Apple Inc.
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, rebranded "M ...
, 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, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
'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 strings (e.g., words) are to one another, that is measured by counting the minimum number of operations required to ...
,
soundex, 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 sp ...
calculations.
See also
*
Human factors
Human factors and ergonomics (commonly referred to as human factors) is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Four primary goals of human factors learnin ...
*
Human reliability
Human reliability (also known as human performance or HU) is related to the field of human factors and ergonomics, and refers to the reliability of humans in fields including manufacturing, medicine and nuclear power. Human performance can b ...
*
Murphy's law
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 about how design serves as the communication between object and user, and how to optimize that conduit of communication in order ...
.
External links
Publications by SoarTech (may rather be changed or removed) (pdf)Making reliable distributed systems in the presence of hardware errors (thesis, pdf, long)
{{Design
Error
Fault-tolerant computer systems
Computer errors
User interface techniques