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Our human factors specialists perform a wide range of analyses that contribute to the design of safe, effective, and usable products, as well as comply with regulators’ expectations regarding the application of human factors in product design. Our human factors “toolkit” contains many types of analyses that focus on mental and physical interactions with products. 

A comprehensive, use-related risk analysis is central to developing a safe product, and we have completed many in collaboration with and on behalf of our clients.

Use-Related Risks Analysis for Medical and Consumer Products

Our technical approach to use-related risk analysis calls for the identification of possible use errors associated with possible use scenarios. We consider all of the ways that people could make a mistake while interacting with a product in the presence of various performance-shaping factors. An example of this is considering the mistakes that could occur when a paramedic operates a patient monitor/defibrillator while caring for a critically ill patient being transported during the night in an air ambulance experiencing turbulence.

We identify potential use errors by several means. Then, we estimate the severity of potential harms arising from the use errors and the likelihood of the error occurring. While the severity of the potential harm and the likelihood of the error factor into risk estimation, it is the level of potential harm that most determines what risk mitigations should be pursued.

How We Identify Potential Use Errors

Task Analysis

We can study the flow of user tasks as they relate to a product’s user interface, which might be in a preliminary, refined, or final product form. Typically, our analysis involves identifying the sequence and interrelationships of discrete [P]erceptions, [C]ognitive steps, and [A]ctions (often referred to as PCA analysis and referenced in FDA’s guidance regarding the development of medical devices). The analysis provides high visibility on where there is potential to reduce the chance of use errors and to increase interaction efficiency.

Task Analysis

Hazard Analysis

Our hazard analyses are a complement to our task analyses. Instead of looking at a task flow and considering what use errors could lead to harm, a hazard analysis assumes a harm and then considers what errors could cause it.  Therefore, we might start our analysis by assuming harms of the following forms: burns (thermal and chemical), electrical shock, biological contamination (i.e., infection), radiation exposure, and various types of physical and even emotional trauma. Then, our job is to analyze what use errors and other factors could lead to the harm.

For example, we might link an electrical shock to a user inserting a patient monitor lead into a power receptacle rather than a data transfer port. Recognizing such as threat to safety, our analysts can recommend that leads be shaped so that they cannot be inserted into an AC power supply and, most likely, could only fit into the proper sensor cable port.

Known Problems Analysis

It’s smart to consider how products similar to the one being developed have failed and what mistakes people have made when using the products. Accordingly, there is high value in performing a known problems analysis (KPA), which may be considered a structured initiative to learn from the past.

Analysis inputs include a review of information (i.e., reports) found in available adverse event databases (e.g., MAUDE), available data in customer complaints systems, and insights from product trainers and users.

The end product of our analysis is usually a list of problems, articulated in terms of how a user interface feature induced a use error. These insights can be converted into design specifications intended to eliminate use error vulnerabilities in the product under development.

Adverse Event Analysis

Our human factors specialists are frequently called upon to study adverse events and determine their most likely root causes. Some cases:

  • Determine how the user interface of a surgical suction system might have induced members of surgical teams to apply high-pressure suction to a passive chest drain, thereby causing fatal lung injuries.
  • Determine how the user interface of a hemodialysis machine induced dialysis nurses and technicians to overlook that the machine was removing too much fluid from patients, thereby causing hypervolemia (lack of fluid in the body) leading to death or injury.
  • Determine how the user interface of an automated external defibrillator induced users to conduct battery tests in a way that inadvertently left the device discharged and unable to function when it was needed to save persons experiencing life-threatening arrhythmias.

Our analyses involved studying the user interaction details of the adverse events, reviewing the human factors suitability of the product’s user interface, and considering other performance-shaping factors to develop a hypothesis of how a design flaw induced the adverse event. Sometimes we find such a flaw and other times we conclude that the user interface was not a contributing cause.

Anthropometric Analysis

Our specialists are well versed at the long-established science of anthropometric analysis. We draw upon extensive data on the size, shape, strength, range of motion, and other physical characteristics of human beings to perform geometric studies (both 2D and 3D). These studies help us determine how well a product is matched to the intended users’ physical traits. In practice, we have performed such analyses to determine the following:

  • Whether CAT scanner operators will be able to reach controls on a control panel on a varying inclined surface.
  • How much force a 5th percentile female can apply to a lever to open a malfunctioning, semi-automated drug delivery machine in an emergency.
  • The proper dimensions of a surgical instrument so that it can be held comfortably and actuated properly by individuals with very large hands as well as those with very small hands.
  • The proper size and placement of components comprising a sit-stand workstation that is operated by surgeons performing robot-assisted surgery.

Questions? Request more information from our specialists


Meet Emergo at Hospitalar , May 21, 2019 to May 24, 2019 in São Paulo, Brazil


User research leads to a richer understanding of the factors controlling the quality of user interactions with your product.

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Our human factors “toolkit” contains many types of analyses that focus on mental and physical interactions with products.

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Our medical device UI design approach leverages user research to achieve functional and aesthetic goals.

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Summative usability testing, formative usability testing, expert critiques, heuristic analyses, cognitive walkthroughs, and more.

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We want to make the world safer and better through HFE research, training, consulting, and program development.

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Michael Wiklund

General Manager, HFR&D
Allison Strochlic

Allison Strochlic

Research Director

Merrick Kossack

Research Director

Mary Burton

User Experience Director

Richard Featherstone

Research Director
Mark Tavano

Mark Tavano

Director, Sales - HFR&D

Coming soon: Designing for Safe Use (CRC Press, late 2018)

by Kimmy Ansems, Cory Costantino, Alix Dorfman, Brenda Van Geel, Jonathan Kendler, Rachel Aronchick, Valerie Ng, Ruben Post, Jon Tilliss, and Michael Wiklund

We – this book’s authors/designers – are members of the Human Factors Research and Design (HFR&D) at EMERGO by UL. In this book, we have consolidated the lessons we have learned about designing for safe use, that is, designing products that shield people from harm to the extent possible.

We settled on a target of 100 principles on how to make products safer. The principles pertain to hardware, software, document, and document design. Yes, settling on an even one hundred principles was a bit arbitrary and cliché. The myriad ways to design for safe use do not stop sharply at one hundred. But, we think we covered many of the key ones.

We elected to use the term “product” broadly to cover things one might consider to be systems, machines, equipment, instruments, tools, applications, manuals, and instructions. These are all things that need to be designed properly to eliminate or reduce the chance of harm due to normal use and foreseeable misuse.

Most of the design principles could be addressed in an expanded form; even an entire book of its own. We choose brevity for the sake of communicating core concepts with some fun facts to spice things up.

As you read the book, be mindful that the science and art of making things safe is ever changing and that some of the content we present is sure to age. So, complement our guidance with insights you may gain from other sources, ranging from books to technical articles to standards and more.

Usability Testing of Medical Devices - Second Edition

by Michael Wiklund, Jonathan Kendler, and Allison Strochlic

Usability Testing of Medical Devices covers the nitty-gritty of usability test planning, conducting, and results reporting. The book also discusses the government regulations and industry standards that motivate many medical device manufacturers to conduct usability tests.

Since publication of the first edition, the FDA and other regulatory groups have modified their regulations and expectations regarding how medical device manufacturers should approach usability testing. Reflecting these changes, this Second Edition provides updated guidance to readers with an interest or direct role in conducting a usability test of a medical device or system. Key updates involve the 2011 FDA guidance on human factors engineering, requirements set forth by the third edition of IEC 60601 and closely related IEC 62366-1:2015, linking usability test tasks to risk analysis results, and analyzing root causes of use errors that occur during usability tests.

Written by seasoned human factors specialists, Usability Testing of Medical Devices, Second Edition is an informative, practical, and up-to-date handbook for conducting usability tests of medical devices. The book helps ensure a smooth and painless development process―and thus, safe and effective medical devices. Buy the book.

Writing Human Factors Plans and Reports for Medical Technology Development

By Michael Wiklund, Laura Birmingham, and Stephanie Larsen

This book provides the foundation for developing specific human factors engineering (HFE) work products that are needed to meet the FDA's human factors engineering (HFE) guidance. The authors have created a fictitious company and product to generate concrete examples of the plans and reports developed during various stages of HFE. The book includes an HFE project plan, a formative usability test plan and report, a summative (i.e., validation) usability test plan and report, and an HFE report. These work products and additional content outline the activities necessary to develop safe and effective medical devices, making this book an ideal resource for anyone interested in the medical technology field. Buy the book.

Medical Device Use Error Root Cause Analysis
by Michael Wiklund, Andrea Dwyer, and Erin Davis

This book offers practical guidance on how to methodically discover and explain the root cause of a use error―a mistake―that occurs when someone uses a medical device. Covering medical devices used in the home and those used in clinical environments, the book presents informative case studies about the use errors (mistakes) that people make when using a medical device, the potential consequences, and design-based preventions.

Using clear illustrations and simple narrative explanations, the text:

  • Covers the fundamentals and language of root cause analysis and regulators’ expectations regarding the thorough analysis of use errors
  • Describes how to identify use errors, interview users about use errors, and fix user interface design flaws that could induce use errors
  • Reinforces the application of best practices in human factors engineering, including conducting both formative and summative usability tests 

Buy the book

Handbook of Human Factors in Medical Device Design

Edited by Matthew Weinger, Michael Wiklund, and Daryle Gardner-Bonneau

Developed to promote the design of safe, effective, and usable medical devices, Handbook of Human Factors in Medical Device Design provides a single convenient source of authoritative information to support evidence-based design and evaluation of medical device user interfaces using rigorous human factors engineering principles. It offers guidance on user-centric design supported by discussions of design issues, case studies, and examples. The book sets the foundation with coverage of fundamental topics such as aligning the interactive nature of medical devices to the expected use environments ranging from hospitals and ambulances to patients’ homes, drawing on anthropometric and biomechanical data to ensure that designs match the intended users’ bodies and physical abilities, and conducting usability tests and other evaluations to ensure that devices perform as intended. It then focuses on applied design issues, offering guidance on the design of specific types of devices and designing devices for particular use environments. Adapted in part from established design standards and conventions, the design guidance presented in this work distills professional judgment extracted from the contributing authors’ years of experience in applied analysis and design. Written in true handbook style, each chapter stands alone and includes tables, illustrations, and cross references, allowing you to quickly find the exact information you need. Most chapters begin with a general introduction to the selected topic, followed by the presentation of general and special design considerations and then specific, numbered design guidelines. The book also presents a listing of resources, literature, and website references. It not only focuses on the human factors issues that arise when developing medical devices, it supplies the necessary guidance to resolve them. Buy the book.

Designing Usability into Medical Products
by Michael Wiklund and Stephen Wilcox

Advocating a user-centered approach to medical technology design, Designing Usability into Medical Products covers the essential processes and specific techniques necessary to produce safe, effective, usable, and appealing medical systems and products. Written by experts on user-centered research, design, and evaluation, the book provides a range of alternative approaches to the subject. Wiklund and Wilcox explore how to make medical devices safe and effective by involving users in the design process. They discuss specific design and evaluation methods and tools, present case studies of user-friendly medical technologies and corporate human factors programs, and supply related resources for medical design professionals.

The book conveys an in-depth understanding of the user-centered design process, covers design methods for FDA compliance, and offers guidance on performing a variety of hands-on user research, user interface design, and user interface evaluation. The authors make a compelling case for treating the user's needs and preferences as a top design priority, rather than an afterthought. They demonstrate that high-quality customer interactions with systems and products leads to effective medical diagnosis and treatment, increases the physical and mental well being of patients and caregivers, and leads to commercial success in a crowded marketplace. Buy the book.

Usability in Practice

Editor: Michael Wiklund

This volume investigates how major corporations, such as Microsoft, Borland, Apple, Eastman Kodak, and Silicon Graphics, address usability issues. It presents case studies of each organization, outlining their program structures, program goals, and team members' responsibilities and resources. The book also addresses how usability is marketed inside the organization and to customers, as well as the lessons learned during the course of product development efforts. Each illustrated study includes advice that should help readers establish and manage their own program.

Out of print. Used copies might be available.

The Beauty of Unity-in-Variety

by Ruben Post

Products have the capacity to evoke a sense of beauty or appreciation in us. Whether marveling over a new car, admiring the interface of our next generation smartphone, or wielding a perfectly balanced kitchen knife, we can appreciate perceiving their design. The features of an artifact, arranged and produced from following a plan. However, most of us are rarely aware of what exactly makes a certain product aesthetically appealing – or that aesthetically pleasing products are generally considered more usable as well. This thesis studies how our aesthetic appreciation of products is formed in the visual and tactile sensory domain. It identifies how unity (the degree to which a design comes across as ordered, coherent, and structured as one whole) and variety (the degree of differences, diversity, and number of elements in a design) can together explain our aesthetic appreciation for products. Furthermore, it identifies ways to influence unity and variety to create the most aesthetically pleasing designs.

Available at Institutional Repository, Delft University in Delft, The Netherlands. Contact Ruben Post at ruben.post@ul.com.