---
title: 5 principles to help you think like a human factors professional
url: "https://www.systra.com/australia/news/thing-like-a-human-factors-professional/"
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date_published: 2022-08-30
date_modified: 2022-10-14
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reading_time: 13 min
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categories:
  - General
tags:
  - Human factors
---

# 5 principles to help you think like a human factors professional

![Sydney, Circular Quay](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/09/services-operational-integration-human-factors.png)

In this article I have identified 5 principles to help you think more like a
human factors professional when involved in the design of new equipment. The
principles are based on my experience of practicing human factors in high hazard
industries.

Whilst I would always advocate the involvement of human factors professionals,
particularly for complex and safety critical projects, my hope is that these
simple principles can help you ask the right questions, apply some basic
principles, and help you to identify when you need to call in an expert.

Throughout this article I will use a made-up project example of a customer help
point to illustrate different methods and the benefits of applying each
principle. Customer help points, like those typically found at train stations,
are used to provide customers with service information and can be used in an
emergency. Pressing the buttons will connect a customer with the appropriate
person, or provide an automated response. I must stress that I haven’t worked on
this project, I have merely picked it as an example.

![hf_blog1](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog1.jpg)

_(Figure 1 Example project, customer help point)_

## 󠀁**1\. Understand your users**󠁿

Start by identifying all the users of your new equipment. In Human Factors we
refer to this as “defining the target user population”. The users will vary from
project to project, so identifying who they are at the outset will help you make
informed decisions to suit their needs. Consumer facing products, such as our
customer help point, need to cater for a wide range of potential users
(including different ages, shapes and sizes, strengths etc). However, for
products in specialist domains your target user population may be different.
Perhaps there are job selection criteria that define minimum and maximums. An
example of this is train drivers, who have minimum requirements for visual
acuity, for obvious reasons. Here are a few tips that will help you to ensure
your product or system is fit for purpose and adequately considers the
capabilities and limitations of your users.

Consider the physical attributes of users: When considering the physical
attributes of a user, human factors specialists most frequently employ a design
philosophy, wherein the design is developed to account for the extreme users of
the target population. This is most commonly defined as the 5th percentile
female and the 95th percentile male (this can be for any piece of anthropometric
data of interest, such as stature, reach, of weight). Due to the normal
distribution of key physical and cognitive attributes across a sample
population, if you demonstrate that the design is suitable for these extreme
users, you in turn demonstrate its suitability for the wider population. This
concept is illustrated in Figure 2, which provides an illustration of the normal
distributions of female and male stature.

![hf_blog2](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog2.jpg)

_(Figure 2 Example normal distribution for female and male stature)_

Consider cognitive and behavioural attributes: Personas are a powerful tool to
consider the capabilities and goals of your target users. Personas are a
user-centred design approach most commonly used in user experience design,
though increasingly used within the rail industry, particularly in station
design. A persona is a fictional character representing a major user from your
target audience. The personas will describe the users’ needs, experiences,
behaviours and goals. The use of personas help maintain focus on end-user needs
throughout the design process. In the case of our customer help point, the
personas should include a wide range of potential users, including passengers or
reduced ability and mobility. A point I discuss further below.

Consider inclusive design: Wherever possible I would advocate the application of
inclusive design principles, this is often called “Design for all” or “Universal
Design”. Inclusive design seeks to accommodate the widest possible range of
potential users by not unduly excluding users of different abilities.

I’d encourage readers to use the Inclusive Design Toolkit developed by Cambridge
University (
[www.inclusivedesigntoolkit.com](http://www.inclusivedesigntoolkit.com/)) [1].
Figure 3 from the afore mentioned website illustrates the diversity across the
population, and the target population for inclusive design.

![hf_blog3](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog3.jpg)

_(Figure 3 Target for inclusive design from www.inclusivedesigntoolkit.com)_

The Toolkit provides the following categories for capabilities; vision, hearing,
thinking, reach and dexterity, and mobility. The demands that your product or
system imposes can result in difficulty, frustration, or even exclusion of a
much larger group of users than you probably realise. Why not use their free
exclusion calculator to see how many potential users you may be excluding
(calc.inclusivedesigntoolkit.com).

At this point you may be saying ‘inclusive design sounds great, however we do
not have the budget or need on our project’. In many cases the huge increase in
potential customers is a compelling argument. Though it should also be noted
that application of inclusive design principles will benefit all of your
potential users, not just those with reduced ability.

## 󠀁**2\. Think about the tasks**󠁿

Make sure you identify all user tasks relevant to your new piece of equipment. A
Task Analysis (TA) is one of the corner stones of human factors engineering. It
is a technique we routinely employ to provide a step-by-step description of the
goals, tasks, and sub-tasks associated with a product or system.

A task analysis can take many different forms, it is not always necessary to
define each sub-task in detail. As a minimum, designers should define a list of
tasks associated with their product. Where a certain task is critical to the
success of your product this list can then be used to derive design
requirements. It can also be used as a checklist to evaluate design options, or
as a more detailed evaluation of your preferred solution. The TA can also be
used as the basis for subsequent analyses, such as Human Error Identification
(HEI) or Risk Based Training Needs Analysis (RBTNA). Error identification is
discussed in more detail in principle 4.

Figure 4 provides an example of a Hierarchical Task Analysis (HTA), for our
customer help point. An alternative example is provided in Table 1, which
displays the same information in the format of a Tabular Task Analysis (TTA). A
key advantage of the Tabular form is the ability to add additional columns to
capture information about a specific sub-task. This may include any equipment
used, the information needs (i.e. what a user needs to complete this step), or
task relevant contextual information (explored further in principle 3).

![hf_blog4](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog4.jpg)

_(Figure 4 Example HTA for getting rail service information from customer help point)_

![hf_blog5](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog5.jpg)

_(Table 1 Example TTA for getting rail service information from customer help point)_

## 󠀁**3\. Understand the context and consider the overall system**󠁿

It is critical that you consider the context in which the tasks will be
performed. This is one of the key areas of focus for HF professionals, but why
is it so important? The wider workspace and physical environment have a big
impact on how users interact with your product, for instance:

- If your product is designed to be used outdoors then the physical environment,
  including the weather, could have a big impact. For our customer help point
  the physical environment will affect where we position the unit, we must
  ensure there is sufficient room to access and operate the help point. It also
  requires us to consider the impact of rain and sun (glare) on task performance
  and design.
- The thermal environment can also be a factor. Cold environments will affect
  dexterity and strength, whilst heat will affect vigilance and endurance.
- Finally, the sonic environment can have a big impact on task performance and
  wellbeing. This is a phenomenon well understood by anyone who has struggled to
  maintain focus in a noisy open plan office. In the case of customer help
  point, the location and design of the unit will have an impact on our ability
  to communicate with an advisor in what can be a noisy environment.

Considering this larger system and overall context of use will help you make
much better-informed design decisions and avoid costly, or even dangerous
mistakes. In principle 2 we explored human interaction with a system, now we
must recognise that this interaction does not take place in a vacuum.

This concept is well illustrated in the ‘onion’ model. The model includes the
wider context and the various layers of influence. The users, their tasks, and
the equipment (your product) form the core of the model. The inner layers of the
onion represent tangible impacts on a user or system and tend to be well
understood. However, the outer layers are more likely to be overlooked. As you
work your way outward there are additional influences (ranging from financial,
technical, legal and social) that can have a huge impact of the success or
failure of your product.

![hf_blog6](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog6.jpg)

_(Figure 5 ’Onion’ model, adapted from Wilson and Corlett [2])_

I recommend trying to identify these external factors – in some instances they
may represent latent failures which can have a huge impact. In the case of our
customer help point, a simple example could relate to maintenance. External
influences could mean that maintenance is limited in time, equipment, and
competence, and therefore ease of maintenance should be a key requirement of
your design.

## 󠀁**4\. Think about the errors that people might make**󠁿

In high hazard industries, a detailed analysis of potential human errors is an
activity best led by a human factors professional. However, in your role as a
project engineer, project manager, subject matter expert, or end-user, you are
fundamental to this process.

All engineering projects will include some form of hazard identification. This
may include Safety in Design (SiD), Preliminary Hazard Analysis (PHA), Hazard &
Operability Analysis (HAZOP), Hazard Identification studies (HAZID), or many
other similar techniques. These qualitative assessment techniques each seek to
identify hazards, along with existing and proposed controls. In the absence of a
dedicated Human Errors Identification (HEI) work package, these forums provide
the best opportunity to identify and mitigate potential human errors.

In my experience, consideration of potential human errors within these
safety-led techniques is dependent upon the experience of the workshop
facilitator, and the guidewords / prompts they use in the session. Furthermore,
where users are considered, the hazards typically relate to workplace health and
safety – think trips, slips and falls. Whilst inclusion of these is important,
focussing on these alone will likely omit much more serious human errors with
more severe consequences. As a starting point I would suggest the inclusion of
human factors related guidewords in whichever hazard identification technique
you choose to use, two examples are provided below.

One option is to use an error taxonomy based on Reason’s model [3] of human
error types. The error types are further categorised using Rasmussen’s Skill,
Rule, and Knowledge model [4] which provides insights to the human behaviour
and decision making leading to the human error.

![hf_blog7](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog7.jpg)

_(Figure 6 Reason and Rasmussen model of human error, from [5])_

Referring back to our customer help point example. My preferred HEI technique is
the Systematic Human Error Reduction and Prediction Approach (SHERPA).
Completing a SHERPA analysis at the design stage would help you identify
potential errors that could be expensive to rectify or have adverse consequences
on system performance. An example SHERPA analysis is provided below, building on
the Task Analysis presented in principle 2.

![hf_blog8](https://www.systra.com/australia/wp-content/uploads/sites/9/2022/08/hf_blog8.jpg)

_(Table 2 Example extract of SHERPA analysis)_

## 󠀁**5\. Consider the physical demands of your product**󠁿

Of course my top 5 principles had to include something about physical
ergonomics. Perhaps the topic people most frequently associated with the human
factors discipline. I’ve included this as the final principle as successful
application is dependent upon two afore mentioned principles, namely:
understanding your users, and thinking about the tasks they will perform.

Physical ergonomics assessments seek to achieve the best possible ‘fit’ between
a product and its users. This can have many positive results, including:

-  Increased productivity
- Improved ease of use
- Eliminate or minimise risk of injury

In the case of our customer help point, accessibility standards mandate the
height of the unit. Compliance with any applicable standards is obviously the
starting point, however there are other physical ergonomics considerations that
you should be aware of. These considerations will be informed by your task
analysis, or task list from principle 2.

In NSW the Assets Standards Authority (ASA) stipulate that “Help points shall be
positioned within a height range of 700mm and 1250mm so that the user is able to
access the functional components of the help point unit”. This range has been
defined to ensure wheelchair users can operate the help point however this is
likely to be below the optimum working height for our tallest potential users,
here defined as a 95th percentile male.

A 95th percentile Australian male has a stature of 1898mm and a standing elbow
height of 1219mm (both including a 25mm footwear adjustment). Therefore, if
placed at the lower end of the range, a taller male will be required to bend to
view the help point display and to operate the controls, microphone, and
speaker. This is where we make use of the considerations from the task analysis,
such as task frequency, task length etc. As using a help point is a very
infrequent task and the duration of use is short, these non-optimum postures
would still be considered acceptable, even for a 95th percentile male.
This example illustrates how anthropometric data can be used in combination with
your tasks to assess a design. If a poor fit between your product and user has
the potential to cause injury, or inability to use your product, you should
create design requirements to address the mismatch and optimise the solution for
the widest range of users.

## Reference List

1\. Inclusive Design Toolkit developed by Cambridge University (
[www.inclusivedesigntoolkit.com](http://www.inclusivedesigntoolkit.com/))

2\. Wilson, J & Corlett, N, Evaluation of human work, Taylor & Francis, Second
Edition, 1991

3\. Reason, J. Human Error, Cambridge University Press, 1990

4\. Rasmussen, J. Human errors: a taxonomy for describing human malfunction in
industrial situations, J. Occupational Accidents, pp. 311 – 333, Vol. 4, 1982.

5\. Human error in plant maintenance, 2018, 
[https://www.maintenanceandengineering.com/2018/04/06/human-error-in-plant-maintenance/](https://www.maintenanceandengineering.com/2018/04/06/human-error-in-plant-maintenance/)

## Find out more

If you would like to know more about the Human Factors services that we offer at
SYSTRA, visit the 
[main page.](https://www.systra.com/australia/services/operational-integration/human-factors/)

**Categories:** General
**Tags:** Human factors