Adonis Diaries

Posts Tagged ‘Random errors

Article #12, April 9, 2005

“What are the error taxonomies in Human Factors?”

There is a tendency to separate errors made by human and those done by machines as if any man made equipment, product, or system has not been designed, tested, evaluated, manufactured, distributed, or operated by a human.  My point is any errors committed by using or operating an artificial implement that causes injuries is ultimately a human errors. 

How Human Factors classifies errors when people operate systems, and what are the types of errors, their frequencies and consequences on the health and safety of operators and systems’ performance?  Human Factors professionals attempted to establish various error taxonomies, some within specific contexts such as nuclear power plants and chemical installations, of deficiencies in design and operation that might be committed, and others that are general in nature and restricted to processes of the mind and the limitations of human capabilities. One alternative classification of human errors is based on human behavior and the level of comprehension; mainly skill-based, rule-based, or knowledge-based behavioral patterns. For example, Rasmussen (1982) developed a decision flow diagram that identifies 13 types of errors; this taxonomy identifies two kinds of errors attributable to skill based behavior such as acts relevant to manual variability or topographic misorientation, four major errors related to rule based behavior such as stereotype takeover, forgetting isolated acts, mistakes alternatives, and other slip of memory, and then seven types of errors that can be attached to knowledge based behavior such as familiar association short cut, information not seen or sought, information assumed but not observed, information misinterpreted, and side effects or conditions not adequately considered. 

These types of errors are the products of activities done in routine situations or when the situation deviates from normal routine and discriminate among the stages and strength of controlled routines in the mind that precipitate the occurrence of an error whether during executing of a task, omitting steps, changing the order of steps, sequence of steps, timing errors, inadequate analysis or decision making.  With a strong knowledge of the behavior of a system, provided that the mental model is not deficient, then applying the rules consistently most of the errors will be concentrated on the level of skill achieved in performing a job.

Another taxonomy rely on the theory of information processing and it is somehow a literal transcription of the experimental processes; mainly observation of the status of a system, choice of hypothesis, testing of hypothesis, choice of goal, choice of procedure and execution of procedure.  Basically, this taxonomy may answer the problems in the rule-based and knowledge–based behavior.

Another alternative taxonomy could be found in measurement errors considered in statistical research such as conceptual, consistent or random errors. Conceptual errors are committed when a proxy is used instead of the variable of interest either because of lack of knowledge of how to measure the latter (i.e., measuring vocabulary ability when mental ability is the object of the research) or because it is less expensive or more convenient.

Consistent errors are represented by systematic errors from respondents whether conscious or not, measuring instruments, research settings, interviewers, raters, and researchers. Consistent errors affect the validity of measures.

Random errors occur as a result of temporary fluctuations in respondents, raters, etc.  Random errors affect the reliability of the measures.

The effects of these measurement errors have different consequences whether committed relative to the dependent or independent variables. It would be interesting to find correspondence among the various error taxonomies as well as assigning every error to either a conscious, predetermined tendency along with the real reasons underlining these errors, or unconscious errors.

It is useful to specify in the final steps of taxonomy whether an error is of omission or of commission.  I suggest that the errors of commission be also fine tuned to differentiate among errors of sequence, the kind of sequence and timing of the execution.

There are alternative strategies for reducing human errors by either training, selection of the appropriate applicants or redesigning a system to fit the capabilities of end users and or taking care of his limitations by preventive designs, exclusion designs and fail-safe designs.




March 2023

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