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10 Design Principles for Product Development Teams

Much has changed since we introduced our “Design Defined” series in 2019, but one thing remains the same: our commitment to sharing our favorite design principles! We’ve amassed a library of thirty videos and blog posts featuring (and authored by) Bresslergroup strategists, researchers, designers, and engineers.

In 2020 and 2021, we published roundups of Volumes 1 and 2 of Design Defined, with lots of links provided to dig deeper:

• Read about the design principles in Volume 1: 10 Design Principles for Better Products
• Read about the design principles in Volume 2: 10 More Design Principles for Better Products

And this roundup of Volume 3 features our latest batch of ten:

01. Jobs, Outcomes, Constraints
02. IoT Data Collection
03. Root Cause Probing
04. Non-Finito Prototyping
05. Calm Technology
06. Plough Hypothesis
07. T-Shaped Skills
08. Affordance
09. Miller’s Law
10. Pareto Principle


01. Jobs, Outcomes, Constraints

Jobs, Outcomes, and Constraints (JOC) is a framework for evaluating the needs observed during research and ranking them in terms of importance.

How can the JOC framework improve product design?
By pausing to consider Jobs, Outcomes, and Constraints between research and ideation, you can ensure you’re solving the problems that matter most to your users and business.

What are Jobs, Outcomes, and Constraints?:

  • A Job is the task a customer “hires” a product to perform; it can serve a functional, emotional, or social purpose.
  • An Outcome is a metric a customer uses to measure the success of a Job; it can help reduce the influence of preconceived notions.
  • A Constraint is an imposed restriction or limitation that keeps the user from getting the Job done; it can help product design teams choose between two ideas.

Find out more about Jobs, Outcomes, and Constraints:
– Watch the Design Defined: Jobs, Outcomes, Constraints video
– Read our blog post, “Use ‘Jobs, Outcomes, and Constraints’ To Exploit the Pause Between Research and Ideation


02. IoT Data Collection

Decisions about IoT data collection are central to every intelligent product’s development because they have a powerful ripple effect on the product’s design. IoT data collection impacts data deployment, storage, sensor selection, processing power, security, and more.

How can user needs inform your data collection strategy?
User needs will drive decisions about what data is required, what sensors are able to collect that data, and how you will connect to the Internet to transmit that data.

Three things to know about IoT Data Collection:

  • It can be tempting to let the latest tech drive your product, but data collection decisions should be driven by your users’ needs.
  • Decide which data you need to collect before deciding which sensors you’ll use.
  • A lot rides on how your IoT device connects to the Internet and transmits data. This determines how a user will interact with your device, and it will drive cost and power consumption.

Find out more about IoT Data Collection:
– Watch the Design Defined: Data Collection for Connected Devices video
– Read our blog post, “Why IoT Data Collection Is Essential To Get Right


03. Root Cause Probing

Root Cause Probing can help medical device designers predict misuse and proactively prevent it, ultimately preventing recalls, avoiding patient harm, and potentially saving lives.

What is Root Cause Probing?
Root Cause Probing is the art of watching for user errors, trying to understand why they occurred, and digging deeper to uncover what went wrong.

Three things to know about Root Cause Probing:

  • An unintentional medical device error is never the user’s fault; the medical device manufacturer must accept fault, so designers should focus on how the user interface may have led to the error.
  • During user testing, it’s important to let users complete a workflow before you ask why they did something wrong — and to use light language when questioning their actions.
  • To probe deeper, follow each “why” question with another “why” question.

Find out more about Root Cause Probing:
– Watch the Design Defined: Root Cause Probing video
– Read our blog post, “How Root Cause Probing Improves Medical Device Design


04. Non-Finito Prototyping

Non-Finito Prototyping deliberately gives users an unfinished product to observe how they might complete the workflow or experience without any guidance.

How can Non-Finito Prototyping inform your product design process?
Rather than creating a complete workflow or experience and seeing if we got it “right” during testing, we can leave a hole in the experience. Seeing how the end user might fill this hole can inform and inspire the design.

Three things to know about Non-Finito Prototyping:

  • Being able to interact with a physical prototype while looking at an unfinished interface allows users to think critically about the most useful and relevant information they would need to receive.
  • Rather than a “discount” prototyping approach, non-finito is an exploratory feedback method for continuing to discover needs as you’re moving beyond a product’s core workflow.
  • If you’ve ever used the “Poke” feature on Facebook, you’ve used a non-finito product.

Find out more about Non-Finito Prototyping:
– Watch the Design Defined: Non-Finito Prototyping video
– Read our blog post, “Non-Finito Prototyping: A New Technique for Digital-Physical Product Design.”


05. Calm Technology

Calm technology communicates the information a user needs at the VERY moment they need it, without hijacking their attention or inducing heightened emotions.

How can product designers create Calm Technology?
Designers should consider all forms of feedback (haptic, audio, and visual) to come up with the calmest solution. In general, use the minimum amount of technology needed to solve a problem.

Three things to know about Calm Technology:

  • Push notifications and the constant buzzing and dinging of our devices represent the opposite of Calm Technology.
  • The concept dates back to the 1990s when a group of researchers at Xerox wondered how a future of “ubiquitous computing” might communicate information without hijacking a person’s attention.
  • In 2015, researcher and designer, Amber Case, inspired a new rally cry in her book Calm Technology, writing: “A person’s primary task should not be computing, but being human.”

Find out more about Calm Technology:
– Watch the Design Defined: Calm Technology video
– Read our blog post, “Calm Technology in an Era of Push Notifications


Blooper break:

Enjoy bloopers from our Volume 3 video shoots, featuring Trisha Ambe, Dan Marcq, Chris Murray, Jes Koepfler, Jemma Frost, Aaron Pavkov, Winnie Lee, Mathieu Turpault, Sharon West, Pete Wisber; and Lily Wolf, behind the scenes.


06. Plough Hypothesis

The Plough Hypothesis explains the connection between ancient farm tools and modern gender inequality and provides a cautionary lesson for today’s product designers.

What do ancient farm tools have to do with modern gender inequality?
It’s unlikely that the inventors of the plough intentionally built a tool that was better suited for men, but most products are inherently designed for men due to a gender data gap. In the case of the plough, this had a powerful ripple effect that influenced the evolution of gender norms in certain societies.

Three things to know about the Plough Hypothesis:

  • Before the invention of the plough, men and women in farming communities worked the fields together, but the plough required physical abilities that sidelined women. Generations later, women in these societies are less likely to work outside the home.
  • The traditional three-stone stove used by 80 percent of the developing world is a contemporary example of a tool that exacerbates gender inequity.
  • For most of recorded modern history, the default person that we design for has been a male person. As a result, most of the world’s data is based on the male body and male experiences. This has created a significant gender data gap.

Find out more about the Plough Hypothesis:
– Watch the Design Defined: The Plough Hypothesis video
– Read our blog post, “The Plough Hypothesis and Design’s Gender Data Gap


07. T-Shaped Skills

T-Shaped is a way to describe someone’s knowledge and skills when that person has both a wide breadth of skills and a deep specialization in one main area of education or work.

Why is T-Shaped an ideal shape for product designers?
T-Shaped individuals tend to be curious, clever collaborators who can crack the toughest product design riddles when they work together.

Three things to know about T-Shaped Skills:

  • The vertical portion of the “T” describes the depth of expertise in a main area of education and work experience; the horizontal portion of the “T” describes the breadth of skills and experience.
  • Hobbies that foster creative thinking — like photography, music, and sketching — can help to broaden our “T.”
  • The term was initially coined by McKinsey & Company in the 1980s and was later popularized in the context of product design by IDEO’s CEO Tim Brown.

Find out more about being T-Shaped in product design:
– Watch the Design Defined: T-Shaped video
– Read our blog post, “Why T-Shaped is the Best Fit for Product Design


08. Affordance

Affordance is the relationship between what something looks like and how it’s used — a user should be able to figure out how to use something just by looking at it.

How does Affordance make medical devices safer?
If a medical device has poor affordance and users can’t tell how to use it just by looking at it, the design could lead to user error and patient harm.

Three things to know about Affordance:

  • If you’ve ever pulled a door that you were actually supposed to push, you’ve had a run-in with a “Norman Door” — a classic example of poor affordance!
  • Researchers look for potential use errors during usability testing. It’s important to do this research early so designers can use these insights to build affordance and signifiers into their products.
  • Signifiers, such as an arrow on a cap that shows you how to remove it, are cues that improve affordance by helping users understand how to use a product.

Find out more about Affordance:
– Watch the Design Defined: Affordance video
– Read our blog post, “How Affordance Makes Medical Devices Safer


09. Miller’s Law

Miller’s Law tells us that the average person can only hold roughly seven items in their short-term memory at one time — or as Miller put it, “the magical number seven, plus or minus two.”

How can Miller’s Law inform the design process?
Miller’s Law can be a helpful tool for deciding how many concepts to present to a client during the initial design review — we suggest presenting clients with four to six options.

Three things to know about Miller’s Law:

  • Cognitive psychologist George Miller developed Miller’s Law in 1956.
  • Once you know this theory, it’s easy to spot it in the world around you, often in the form of “chunking,” or organizing content into smaller clusters that are easier to process and remember.
  • For designers, the challenge is to determine which features or information are most important and how to limit options or create a visual hierarchy that centers just seven (+/- two) items.

Find out more about Miller’s Law:
– Watch the Design Defined: Miller’s Law video
– Read our blog post, “Use Miller’s Law When Presenting Design Concepts


10. Pareto Principle

The Pareto Principle states that, for many situations, roughly 80 percent of results will come from 20 percent of causes.

How can the Pareto Principle guide a product design team?
A design team can use Pareto Principle as a framework to focus their energy and effort by asking: What are the features that are going to guarantee the function and usefulness of this product? What are the vital few?

Three things to know about Pareto Principle:

  • The Pareto Principle is named for economist Vilfredo Pareto who noted in 1895 that 80% of the land in Italy was owned by 20% of the population. The principle was later applied to quality management by Dr. Joseph Juran, who developed the related term “the vital few.”
  • In product design, we’re searching for which of a “vital few” features will drive most of a product’s impact.
  • There are four considerations that can help you determine the vital few: user needs, product lifecycle, stakeholders, and risk.

Find out more about Pareto Principle:
– Watch the Design Defined: Pareto Principle video
– Read our blog post, “Applying the Pareto Principle to Product Development


Learn more about these product design principles when you download one of our free Design Defined ebooks.