Critical incident technique is a method of gathering facts (incidents) from domain experts or less experienced users of the existing system to gain knowledge of how to improve the performance of the individuals involved.
The critical incident technique (CIT) is used to look for the cause of human-system (or product) problems to minimize loss to person, property, money or data. The investigator looks for information on the performance of activities (e.g. tasks in the workplace) and the user-system interface. Both operators and records (e.g. documented events or recorded telephone calls) can provide such information. The investigator may focus on a particular incident or set of incidents which caused serious loss. Critical events are recorded and stored in a database or on a spreadsheet. Analysis may show how clusters of difficulties are related to a certain aspect of the system or human practice. Investigators then develop possible explanations for the source of the difficulty.
The method generates a list of good and bad behaviors which can then be used for performance appraisal.
Flanagan, J.C. 1954. The critical incident technique. Psychological bulletin, 51(4), 327-358.Flanagan was first to describe the critical incident technique.
Chapanis, A. (1959) Research techniques in human engineering, John Hopkins Press: Baltimore, Maryland.
Ramsey (1977) Accident sequence model.Includes: perception of hazard, cognition of hazard, decision whether or not to avoid hazard, ability to avoid hazard and luck.
Christensen, J. (1985). Human factors in hazard risk evaluation, Human Factors Engineering: Engineering Summer Conference, University of Michigan: Ann Arbour, Michigan.
Reason, J. (1990). Human error. Cambridge University Press: New York.
Nemeth, C. P. (2004) Human factors methods for design - making systems human-centered., CRC Press.Report case where invasive surgical procedure performed in a hospital catheterization laboratory present the potential to inflict serious trauma on the patient. Problems were found in the possibility of contrast dye introducing air bubbles into the patients bloodstream which could affect the nervous system or brain.
Casey, S. (1998) Set phasers on stun: and other true tales of design, technology, and human error, Santa Barbara: Aegean.Contains 20 short stories in the book covering situations from the accidental launching of a rocket to some horrific accidents in hospitals, illustrating how quickly and easily catastrophes can happen.
Benefits, Advantages and Disadvantages
CIT identifies possible sources of serious user-system or product difficulties. The recommendations for improvement try to eliminate the potential for the same situation to result in similar loss. However only actual use demonstrating that the product no longer induces the problem ensures that it is currently safe.
This can be very high as the study may result in major problems or loss being addressed and future losses reduced as a result of the study.
The method is useful when problems occur within a system but their cause (and sometimes their severity) is not known. However the method also takes account of helpful events that may have prevented loss or countered errors.
Participants and Other Stakeholders
Who Can Facilitate
Human factors personnel and task experts with interviewing skills and experience in analyzing human activities. It is helpful to have personnel who are not too close to the situation being investigated who may have difficulty in being objective.
Data Analysis Approach
This can be done using a spreadsheet. Every item is entered as an incident first. Each of the incidents is then grouped into categories. The analyst looks at the frequency of similar incidents and under what conditions are events occur. Possible explanations for the source of the difficulties are generated and validated with the systems staff or participants. The results of a critical incident technique are improvements in the procedures and system to reduce and preferably eliminate the chance of similar incidents re-occurring.
The implemented changes are audited to check that they are effective and similar incidents are not continuing to take place, or resulting in other problems elsewhere in the system.
Costs and Scalability
People and Equipment
The critical incident investigation team may consist of 1 or more investigators depending on the scale of the exercise.
The critical incident investigation team may conduct a study within a few weeks. There is an advantage in conducting a study of a serious incident quickly while relevant staff can remember the details and while associated records exist.
Ethical and Legal Considerations
Interviewees are typical assured of anonymity so that participants can describe how a product operates or what another person did without being divulged as the source of information. This is of particular importance in communities that share a strong bond such as pilots or police officers.
Design teams may be sensitive to a very negative report identifying many usability problems. This can be addressed by grouping problems and offering a constructive approach in suggesting practical solutions. The report should also report the positive aspects of the system identified during the study.