Human error identification techniques applied to public technology: predictions compared with observed use

Identifying and preventing human error in the sugar production process: A multi-stage approach using HTA, HEC and PHEA techniques

This article discusses the importance of identifying and preventing human error in industrial environments, specifically in the sugar production process. The article emphasizes the importance of choosing the right technique for risk assessment studies resulting from human errors. A cross-sectional study was conducted using a multi-stage approach - Hierarchical Task Analysis (HTA), Human Error Calculator (HEC), and Predictive Human Error Analysis (PHEA) - to identify potential human errors in the sugar production process. The HTA, HEC, and PHEA techniques were employed to evaluate each stage of the process for potential human errors. The results of the HTA technique identified 35 tasks and 83 sub-tasks in 14 units of the sugar production process. According to HEC technique 4 tasks with 80 % probability of human error and 2 tasks with 50 % probability of human error had the highest calculated error probabilities. The factors of individual skill, task repetition and importance were the most important factors of human error in the present study. The analysis of PHEA worksheets showed that the number of human errors identified in the tasks with highest probability were 8 errors, of which 50 % were action errors, 25 % checking errors, 13 % selection errors, and 12 % retrieval errors. To mitigate the consequences of human error, it was recommended training courses, raising operator awareness of error consequences, and installing instructions in the sugar production process. Based on the findings, the article concludes that the HEC and PHEA techniques are applicable and effective in identifying and analyzing human errors in process and food industries.

Using systems thinking-based risk assessment methods to assess hazardous manual tasks: a comparison of Net-HARMS, EAST-BL, FRAM and STPA

Formal risk assessment is a component of safety management relating to hazardous manual tasks (HMT). Systems thinking approaches are currently gaining interest for supporting safety management. Existing HMT risk assessment methods have been found to be limited in their ability to identify risks across the whole work system; however, systems thinking-based risk assessment (STBRA) methods were not designed for the HMT context and have not been tested in this area. The aim of this study was to compare the performance of four state-of-the-art STBRA methods: Net-HARMS, EAST-BL, FRAM and STPA to determine which would be most useful for identifying HMT risks. Each method was independently applied by one of four analysts to assess the risks associated with a hypothetical HMT system. The outcomes were assessed for alignment with a benchmark analysis. Using signal detection theory (SDT), overall STPA was found to be the best performing method having the highest hit rate, second lowest false alarm rate and highest Matthews Correlation Coefficient of the four methods.Practitioner summary: A comparison of four systems thinking risk assessment methods found that STPA had the highest level of agreement with the benchmark analysis and is the most suitable for practitioners to use to identify the risks associated with HMT systems.

Human error identification and risk prioritization in LPG unloading operations

Objectives. Errors due to human activities in any operation are analyzed using human reliability analysis in which the principal step is to identify potential human errors followed by quantification and analysis of the error. This work intends to apply a methodology for identifying human errors and to prioritize the risk associated with them in a liquefied petroleum gas (LPG) unloading operation. Methods. The methodology uses hierarchical task analysis which provides the basic framework, along with a systematic human error reduction and prediction approach which aids in identification and categorization of the errors associated with each task with the help of predefined error taxonomy. Also, in order to quantify the risk associated with each identified error, fuzzy failure mode and effect analysis has been adopted. To rank and prioritize the risk associated with each identified error where the individual constituent components are non-commensurable in nature, the VIseKriterijumska Optimizacija I Kompromisno Resenje method has been incorporated. Results and conclusions. Applicability of the methodology presented will help comprehend the severity of risk corresponding to each error at different levels, and the ranking mechanism thus developed in this work aids to prioritize the action to minimize the likelihood of errors.

Resilience engineering on the road: Using operator event sequence diagrams and system failure analysis to enhance cyclist and vehicle interactions

Future visions of transport systems include both a drive towards automated vehicles and the need for sustainable, active, modes of travel. The combination of these requirements needs careful consideration to ensure the integration of automated vehicles does not compromise vulnerable road users. Transport networks need to be resilient to automation integration, which requires foresight of possible challenges in their interaction with other road users. Focusing on a cyclist overtake scenario, the application of operator event sequence diagrams and a predictive systems failure method provide a novel way to analyse resilience. The approach offers the opportunity to review how automation can be positively integrated into road transportation to overcome the shortfalls of the current system by targeting organisational, procedural, equipment and training measures.

Predicting and mitigating failures on the flight deck: an aircraft engine bird strike scenario

Engine damage as a consequence of foreign object debris (FOD) during flight is frequently caused by birds. One approach to minimising disruption caused by this damage is to provide flight crew with accurate information relating to the continuing operational status of the aircraft's engines. Before designing such avionic systems however, understanding of current procedures is needed. Hierarchical Task Analysis (HTA) and Systematic Human Error Reduction and Prediction Approach (SHERPA) were used to identify potential failures that flight crew may make when managing an engine bird strike. Workshops with commercial pilots generated insights into current practice and a commercial pilot SME reviewed outputs for accuracy. Over 200 potential failures were identified, most commonly related to communication. Remedial measures, considering future avionic systems, are proposed to mitigate identified failures. This analysis provides a starting point for future design concepts for assisting flight crew in dealing with engine malfunction due to FOD strikes. Practitioner summary: Hierarchical Task Analysis was conducted to show all tasks involved in dealing with an in-flight aircraft engine bird strike. Systematic Human Error Reduction and Prediction Approach analysis was performed and over 200 possible failures were identified when managing this event. Remedial measures are proposed to help mitigate possible failures.

Making ergonomics accountable: Reliability, validity and utility in ergonomics methods

In this paper, we discuss the ways in which Neville Stanton has challenged himself, his research colleagues, PhD students, the many co-authors and contributors to his publications, and the entire Ergonomics community to determine what it means for there to be 'consistent standards for how [Ergonomics] methods are described and reported.' Only in this way, can it be possible to make claims about whether or not a method in Ergonomics is effective. Given that he is Chartered as both an Occupational Psychologist and an Ergonomist, it is not surprising that he has been concerned with the question of the reliability and validity of Ergonomics methods. In Occupational Psychology, psychometric and personnel selection methods are expected to exhibit acceptable levels of reliability, but this is an expectation which is still somewhat alien to Ergonomics. Neville's work has been instrumental in raising this issue and in providing approaches which can be used to critically evaluate the methods we use. We think that, despite his ground-breaking work, there is still much to do in the Ergonomics community to create the situation for which he has long argued.

State of science: evolving perspectives on 'human error'

This paper reviews the key perspectives on human error and analyses the core theories and methods developed and applied over the last 60 years. These theories and methods have sought to improve our understanding of what human error is, and how and why it occurs, to facilitate the prediction of errors and use these insights to support safer work and societal systems. Yet, while this area of Ergonomics and Human Factors (EHF) has been influential and long-standing, the benefits of the 'human error approach' to understanding accidents and optimising system performance have been questioned. This state of science review analyses the construct of human error within EHF. It then discusses the key conceptual difficulties the construct faces in an era of systems EHF. Finally, a way forward is proposed to prompt further discussion within the EHF community. Practitioner statement This state-of-science review discusses the evolution of perspectives on human error as well as trends in the theories and methods applied to understand, prevent and mitigate error. It concludes that, although a useful contribution has been made, we must move beyond a focus on an individual error to systems failure to understand and optimise whole systems.

Predicting Design-Induced Error on the Flight Deck : An Aircraft Engine Oil Leak Scenario

OBJECTIVE

To explore the types of errors that commercial pilots may make when trying to resolve a suspected engine oil leak using the interfaces currently available.

BACKGROUND

The decisions that pilots make often have to be made quickly and under time pressure, with the emphasis on avoiding critical situations from arising. To make the correct decisions, it is vital that pilots have accurate and up-to-date information available. However, interaction with flight deck interfaces may lead to error if they are not effectively designed.

METHOD

A hierarchical task analysis was conducted using evidence from pilot interview data to understand the pilots' typical response to a suspected engine oil leak scenario. This was used as the primary input into the Systematic Human Error Reduction and Prediction Approach (SHERPA).

RESULTS

A total of 108 possible errors were identified. The most common error type was a retrieval error, in which flight crews may retrieve the wrong information about the engine. A number of remedial measures are proposed to try and overcome such issues.

CONCLUSION

This analysis provides an initial starting point for identifying potential future design ideas that can assist the pilots in dealing with oil leaks.

APPLICATION

This work has identified the value of applying human error identification methodologies to the assessment of current flight deck processes surrounding engine oil leaks. The method presented permits the operational analysis of possible errors on the flight deck and facilitates the proposition of remedial measures to implement technological innovations that can mitigate error.

Evaluation of construct and criterion-referenced validity of a systems-thinking based near miss reporting form

The validity of methods is an ongoing issue in ergonomics. Inconsistent definitions and approaches to evaluation exacerbate this challenge. In this study, the construct and criterion-referenced validity of a new near miss reporting form was evaluated to determine the extent to which it comprehensively captures near miss incidents and is aligned with the systems thinking approach to accident causation. Interview data were used as the reference standard in the evaluation. Using signal detection theory (SDT), a high average hit rate (HR), predictive value (PV) and sensitivity index (SI) were found, with an almost perfect ranking for the index of concordance. The findings show that the reporting form has strong construct and criterion-referenced validity. It is proposed that the approach used in this study could be used by researchers and practitioners when testing the validity of incident data collection tools. Practitioner summary: The validity of methods is a key issue in ergonomics. In this study, we test the validity of a near miss reporting form using interview data as a standard. This approach could be used by practitioners when testing the validity of other ergonomics methods.

Enhancing human performance reliability in aircraft pushback operations

Purpose

The purpose of this paper is to investigate the aircraft pushback operations to predict and manage human errors, particularly those associated with the complex team work of carrying out the pushback operation. This should improve air ramp operations reliability.

Design/methodology/approach

The study applied the human reliability assessment “Systematic Human Error Reduction and Prediction Approach” that involved a total of 60 semi-structured interviews with practicing experts. Past ramp accident reports were also reviewed to provide more in-depth insights to the problem.

Findings

Some of the key performance reliability-degrading errors identified relate to some frequent critical technical inabilities within the team of headset operator and tug driver, as well as the vulnerable intra-team communications. Several best practices were similarly identified.

Practical implications

Based on its findings, this study proposes a new technological concept that can help enhancing safety of aircraft pushback operations. This should enhance reliability of aircraft ground handling and improve aircraft availability. It also provided a generic methodological approach to improve safety-critical operations within high-risk industries.

Social implications

This study responses to the increasing trend in ramp accidents worldwide.

Originality/value

The research conducted to date in this area is still quite limited compared to that of flight and aircraft maintenance safety. The relevant existing studies focus more on ramp safety holistically, and do not go into the details of how safety and reliability of a ramp operation can be improved. The current paper aims at filling this gap.

Neonatal nasogastric tube feeding in a low-resource African setting - using ergonomics methods to explore quality and safety issues in task sharing

BACKGROUND

Sharing tasks with lower cadre workers may help ease the burden of work on the constrained nursing workforce in low- and middle-income countries but the quality and safety issues associated with shifting tasks are rarely critically evaluated. This research explored this gap using a Human Factors and Ergonomics (HFE) method as a novel approach to address this gap and inform task sharing policies in neonatal care settings in Kenya.

METHODS

We used Hierarchical Task Analysis (HTA) and the Systematic Human Error Reduction and Prediction Approach (SHERPA) to analyse and identify the nature and significance of potential errors of nasogastric tube (NGT) feeding in a neonatal setting and to gain a preliminary understanding of informal task sharing.

RESULTS

A total of 47 end tasks were identified from the HTA. Sharing, supervision and risk levels of these tasks reported by subject matter experts (SMEs) varied broadly. More than half of the tasks (58.3%) were shared with mothers, of these, 31.7% (13/41) and 68.3% were assigned a medium and low level of risk by the majority (≥4) of SMEs respectively. Few tasks were reported as 'often missed' by the majority of SMEs. SHERPA analysis suggested omission was the commonest type of error, however, due to the low risk nature, omission would potentially result in minor consequences. Training and provision of checklists for NGT feeding were the key approaches for remedying most errors. By extension these strategies could support safer task shifting.

CONCLUSION

Inclusion of mothers and casual workers in care provided to sick infants is reported by SMEs in the Kenyan neonatal settings. Ergonomics methods proved useful in working with Kenyan SMEs to identify possible errors and the training and supervision needs for safer task-sharing.

Validity and consistency assessment of accident analysis methods in the petroleum industry

Background. Accident analysis is the main aspect of accident investigation. It includes the method of connecting different causes in a procedural way. Therefore, it is important to use valid and reliable methods for the investigation of different causal factors of accidents, especially the noteworthy ones. Objective. This study aimed to prominently assess the accuracy (sensitivity index [SI]) and consistency of the six most commonly used accident analysis methods in the petroleum industry. Methods. In order to evaluate the methods of accident analysis, two real case studies (process safety and personal accident) from the petroleum industry were analyzed by 10 assessors. The accuracy and consistency of these methods were then evaluated. The assessors were trained in the workshop of accident analysis methods. Results. The systematic cause analysis technique and bowtie methods gained the greatest SI scores for both personal and process safety accidents, respectively. The best average results of the consistency in a single method (based on 10 independent assessors) were in the region of 70%. Conclusion. This study confirmed that the application of methods with pre-defined causes and a logic tree could enhance the sensitivity and consistency of accident analysis.

Validating the strategies analysis diagram: assessing the reliability and validity of a formative method

The Strategies Analysis Diagram (SAD) is a recently developed method to model the range of possible strategies available for activities in complex sociotechnical systems. Previous applications of the new method have shown that it can effectively identify a comprehensive range of strategies available to humans performing activity within a particular system. A recurring criticism of Ergonomics methods is however, that substantive evidence regarding their performance is lacking. For a method to be widely used by other practitioners such evaluations are necessary. This article presents an evaluation of criterion-referenced validity and test-retest reliability of the SAD method when used by novice analysts. The findings show that individual analyst performance was average. However, pooling the individual analyst outputs into a group model increased the reliability and validity of the method. It is concluded that the SAD method's reliability and validity can be assured through the use of a structured process in which analysts first construct an individual model, followed by either another analyst pooling the individual results or a group process pooling individual models into an agreed group model.

The application of SHERPA (Systematic Human Error Reduction and Prediction Approach) in the development of compensatory cognitive rehabilitation strategies for stroke patients with left and right brain damage

Approximately 33% of stroke patients have difficulty performing activities of daily living, often committing errors during the planning and execution of such activities. The objective of this study was to evaluate the ability of the human error identification (HEI) technique SHERPA (Systematic Human Error Reduction and Prediction Approach) to predict errors during the performance of daily activities in stroke patients with left and right hemisphere lesions. Using SHERPA we successfully predicted 36 of the 38 observed errors, with analysis indicating that the proportion of predicted and observed errors was similar for all sub-tasks and severity levels. HEI results were used to develop compensatory cognitive strategies that clinicians could employ to reduce or prevent errors from occurring. This study provides evidence for the reliability and validity of SHERPA in the design of cognitive rehabilitation strategies in stroke populations.

To twist, roll, stroke or poke? A study of input devices for menu navigation in the cockpit

Modern interfaces within the aircraft cockpit integrate many flight management system (FMS) functions into a single system. The success of a user's interaction with an interface depends upon the optimisation between the input device, tasks and environment within which the system is used. In this study, four input devices were evaluated using a range of Human Factors methods, in order to assess aspects of usability including task interaction times, error rates, workload, subjective usability and physical discomfort. The performance of the four input devices was compared using a holistic approach and the findings showed that no single input device produced consistently high performance scores across all of the variables evaluated. The touch screen produced the highest number of 'best' scores; however, discomfort ratings for this device were high, suggesting that it is not an ideal solution as both physical and cognitive aspects of performance must be accounted for in design.

PRACTITIONER SUMMARY

This study evaluated four input devices for control of a screen-based flight management system. A holistic approach was used to evaluate both cognitive and physical performance. Performance varied across the dependent variables and between the devices; however, the touch screen produced the largest number of 'best' scores.

A usability evaluation toolkit for In-Vehicle Information Systems (IVISs)

Usability must be defined specifically for the context of use of the particular system under investigation. This specific context of use should also be used to guide the definition of specific usability criteria and the selection of appropriate evaluation methods. There are four principles which can guide the selection of evaluation methods, relating to the information required in the evaluation, the stage at which to apply methods, the resources required and the people involved in the evaluation. This paper presents a framework for the evaluation of usability in the context of In-Vehicle Information Systems (IVISs). This framework guides designers through defining usability criteria for an evaluation, selecting appropriate evaluation methods and applying those methods. These stages form an iterative process of design-evaluation-redesign with the overall aim of improving the usability of IVISs and enhancing the driving experience, without compromising the safety of the driver.

The Design with Intent Method: a design tool for influencing user behaviour

Using product and system design to influence user behaviour offers potential for improving performance and reducing user error, yet little guidance is available at the concept generation stage for design teams briefed with influencing user behaviour. This article presents the Design with Intent Method, an innovation tool for designers working in this area, illustrated via application to an everyday human-technology interaction problem: reducing the likelihood of a customer leaving his or her card in an automatic teller machine. The example application results in a range of feasible design concepts which are comparable to existing developments in ATM design, demonstrating that the method has potential for development and application as part of a user-centred design process.

Relationships between observed and perceived deviations from normative work procedures

Deviations from anticipated courses of events are often associated with accidents, while the effects of deviations that decrease productivity but do not obviously lead to human injury are less clear. A systemic approach to production and safety is introduced, and it is proposed that production deviations have effects that may lead to safety violations and personal injury. In addition, the relationship between observed and perceived production deviations from 12 senior (60-79 years old) males' routine work using three firewood processing machines is analysed. For simple machine work, perceived deviations were positively related to observed deviations per work cycle and inversely correlated to the perception of work efficiency. For more complex machine work it was more difficult to match observers' and operators' perceptions of deviations. Despite challenges in the production deviation concept, this approach offers a holistic understanding of the performance of human-machine-environment systems and complements assessments of deviations from safe working practice.

Predicting pilot error: testing a new methodology and a multi-methods and analysts approach

The Human Error Template (HET) is a recently developed methodology for predicting design-induced pilot error. This article describes a validation study undertaken to compare the performance of HET against three contemporary Human Error Identification (HEI) approaches when used to predict pilot errors for an approach and landing task and also to compare analyst error predictions to an approach to enhancing error prediction sensitivity: the multiple analysts and methods approach, whereby multiple analyst predictions using a range of HEI techniques are pooled. The findings indicate that, of the four methodologies used in isolation, analysts using the HET methodology offered the most accurate error predictions, and also that the multiple analysts and methods approach was more successful overall in terms of error prediction sensitivity than the three other methods but not the HET approach. The results suggest that when predicting design-induced error, it is appropriate to use a toolkit of different HEI approaches and multiple analysts in order to heighten error prediction sensitivity.

The Cochran-Weiss-Shanteau performance index as an indicator of upper limb risk assessment expertise

Ergonomists and many other professionals apply ergonomics principles to musculoskeletal health problems. This study examines whether there are differences when it comes to judgement expertise concerning upper limb disorders (ULDs) between ergonomists and those with less ergonomics training. The Cochran-Weiss-Shanteau (CWS) performance index combines judgement consistency with discrimination into one CWS index. Fifty-eight professionals working in the musculoskeletal health area, from four different professions, judged the likelihood of staff complaining of ULDs in a number of written work scenarios containing ULD risk factors. A student group (n = 148) taking an introductory ergonomics module was used as a reference. The ergonomists scored higher on the CWS index than all of the other groups, performing significantly better than all but the occupational health advisors. Performance improved with increased training level but not with experience. This study suggests that ergonomists are quantifiably different from other ergonomics advisors in their judgement performance in this context. Given the global cost of musculoskeletal disorders, assessing the expertise of those giving ergonomics advice for the management of musculoskeletal health is of great significance. This study presents a method for assessing judgement performance in ULD risk assessment, an important part of musculoskeletal health management.

Human factors in anaesthetic practice: insights from a task analysis

BACKGROUND

Despite a growing recognition of the role of human error in anaesthesia, it remains unclear what should be done to mitigate its effects. We addressed this issue by using task analysis to create a systematic description of the behaviours that are involved during anaesthesia, which can be used as a framework for promoting good practice and highlight areas of concern.

METHODS

The task steps involved in preparing and delivering anaesthesia were identified using hierarchical task analysis (HTA). The systematic human error reduction and prediction approach (SHERPA) was then used to identify potential human errors at each task step and suggest ways of preventing these errors.

RESULTS

The number and type of behaviours involved vary according to the 'phase' of anaesthesia, with tasks in the induction room, including induction of anaesthesia itself, being the most demanding. Errors during preoperative planning and perioperative maintenance could be avoided by measures to support information handling and decision-making. Errors during machine checking, induction, and emergence could be reduced by streamlining or automating task steps, or by making changes to the physical design of the work environment.

CONCLUSIONS

We have demonstrated the value of task analysis in improving anaesthetic practice. Task analysis facilitates the identification of relevant human factors issues and suggests ways in which these issues can be addressed. The output of the task analysis will be of use in focusing future interventions and research in this area.

Applying hierarchical task analysis to medication administration errors

Medication use in hospitals is a complex process and is dependent on the successful interaction of health professionals functioning within different disciplines. Errors can occur at any one of the five main stages of prescribing, documenting, dispensing or preparation, administering and monitoring. The responsibility for the error is often placed on the nurse, as she or he is the last person in the drug administration chain whilst more pressing underlying causal factors remain unresolved. This paper demonstrates how hierarchical task analysis can be used to model drug administration and then uses the systematic human error reduction and prediction approach to predict which errors are likely to occur. The paper also puts forward design solutions to mitigate these errors.

Situation awareness measurement: a review of applicability for C4i environments

The construct of situation awareness (SA) has become a core theme within the human factors (HF) research community. Consequently, there have been numerous attempts to develop reliable and valid measures of SA but there is a lack of techniques developed specifically for the assessment of SA in command, control, communication, computers and intelligence (C4i) environments. During the design, development and evaluation of novel systems, technology and procedures, valid and reliable situation awareness measurement techniques are required for the assessment of individual and team SA, in order to determine the improvements (or in some cases decrements) resulting from proposed design and technological interventions. The paper presents a review of existing situation awareness measurement techniques for their suitability for use in the assessment of SA in C4i environments. Seventeen SA measures were evaluated against a set of HF methods criteria. It was concluded that current SA measurement techniques are inadequate by themselves for use in the assessment of SA in C4i environments, and a multiple-measure approach utilising different approaches is recommended.

Validating task analysis for error identification: reliability and validity of a human error prediction technique

This paper reports on the theoretical and empirical developments for an error prediction methodology called task analysis for error identification (TAFEI). Other researchers have noted the need for theoretically driven approaches that are able to provide practical utility in error prediction. Theoretical developments include the concept of "rewritable routines", which describe the loop between cognitive processing, action and devices states. This has been proposed as a way of unifying ideas from systems theory and cognitive psychology. The empirical research shows that TAFEI is superior to heuristic methods, which supports the idea that structured methods assist in error prediction. The validation study shows that TAFEI reaches acceptable levels in terms of test-retest reliability and concurrent validity. It is believed that the method has reached a level of maturity after 10 years of development work. This is demonstrated by the many uses to which the method has been put, including that of a design tool.

Giving ergonomics away? The application of ergonomics methods by novices

A re-occurring theme in applied ergonomics is the idea of "giving the methods away" to those with little formal education in the subject. Little is known, however, about the reliability and validity of these methods when applied to the design process, for novices or experts. It is important to establish just how well the methods will perform in the hands of the analyst. The study reported in this paper presents data on novice intra-analyst and inter-analyst reliability together with criterion-referenced validity across a range of methods. Considerable variation in the reliability and validity of the methods was found. The data were then used in utility analysis, to determine the cost-effectiveness of the methods for an example of car radio-cassette design. The analysis shows that estimates of cost-effectiveness may help in the selection of methods.

Development and application of a human error identification tool for air traffic control

This paper outlines a human error identification (HEI) technique called TRACEr--technique for the retrospective and predictive analysis of cognitive errors in air traffic control (ATC). The paper firstly considers the need for an HEI tool in ATC, and key requirements for the technique are noted. The technique, which comprises a number of inter-related taxonomies, based around a simple cognitive framework, is then described. A study concerning a real-world application of TRACEr is outlined-the evaluation of several options for reduced separation minima in unregulated UK airspace. In this study, TRACEr was used predictively and retrospectively, looking forward to pre-empt potential problems and looking back to learn from experience. The paper concludes that TRACEr is a valuable aid to design, development and operations in UK ATC, and has indeed been used as a basis for further applications in ATC both in Europe and the USA.

Learning to predict human error: issues of acceptability, reliability and validity

Human Error Identification (HEI) techniques have been used to predict human error in high risk environments for the past two decades. Despite the lack of supportive evidence for their efficacy, their popularity remains unabated. The application of these approaches is ever-increasing, to include product assessment. The authors feel that it is necessary to prove that the predictions are both reliable and valid before the approaches can be recommended with any confidence. This paper provides evidence to suggest that human error identification techniques in general, and SHERPA in particular, may be acquired with relative ease and can provide reasonable error predictions.

Is utility in the mind of the beholder? A study of ergonomics methods

This paper reviews the use of ergonomics methods in the context of usability of consumer products. A review of the literature indicated that there is upward of 60 methods available to the ergonomist. The results of the survey indicated that questionnaires, interviews and observation are the most frequently reported methods used. Ease of use of the methods was dependent upon type of method used, presence of software support and type of training received. Strong links were found between questionnaires and interviews as a combined approach, as well as with HTA and observation. However, a questionnaire survey of professional ergonomists found that none of the respondents had any documented evidence of the reliability and validity of the methods they were using. A study of training people to use ergonomics' methods indicated the different requirements of the approaches, in terms of training time, application time and subjective preferences. An important goal for future research is to establish the reliability and validity of ergonomics methods.