The triple diamond model is a user-centered approach to design and concept development. The first two diamonds really focus on better defining the “what” – who is our customer, what is the job to be done, and what needs are potentially most relevant to them. In this chapter, we turn to the “how”? Given an understanding of the customer and the job to be done, how can we create a great solution? For this, we use the third diamond, another cycle of divergent and convergent thinking.

I want to underscore that the tools and approaches in this chapter have two contexts for application. First, these tools are used to create a great solution concept in the context of zero-to-one product development – say the original concept for the Strava fitness app. Second, these tools can be used in the daily work of individuals and teams for any kind of design challenge, say improving the social networking features within the Strava app, or even for internal innovation problems like how we might increase retention of customers on the Strava platform.

What makes for a great concept?

The goal of the triple diamond model is to deliver a great solution concept. But, what makes for a great concept?

A concept is a preliminary description of how you plan to do the job for the customer.

For physical goods, it’s usually a sketch of the physical embodiment of the solution. For example, here are 10 concepts that were generated by two of the students in my product design class at the University of Pennsylvania to do the job of carrying an ID card, a key, and perhaps a mobile device unobtrusively underneath clothing. They called the resulting product the underwallet. They did a particularly nice job of illustrating these concepts by hand.

For services, the concept is often illustrated with a visual storyboard, or possibly simply with a paragraph of text.

For software, the concept is usually illustrated with the screens that comprise the user interface on a mobile device or desktop computer.

Not all concepts are equally good. Here are the four characteristics that I believe make for a great concept.

1. Addresses Needs

The first and most important characteristics of a great concept is that it addresses the needs of the customer.

Here’s an example. I love Google Docs. The concept is a word processing tool that runs in the web browser with no downloads or installation required. The file is stored in the cloud and is backed up automatically with a history of prior versions. The file can be accessed from any device, including my mobile phone, or from multiple devices simultaneously. Search works great, allowing me to find a document with just a few keystrokes. The software is clean, simple, and fast. I can share a file with anyone or everyone with a couple of clicks. I can export the document as a PDF file if necessary. Other than one tiny complaint about how bullets are formatted, this product is perfect for my needs.

2. Cost Efficient

The second characteristic of a great concept is that it is cost efficient. Here is an example of a cost-efficient packaging concept. Many of you probably know about GLIDE dental floss. It was pioneered by the company WL Gore. It’s made from Teflon or polytetrafluoroethylene. The compound is very slippery and so glide is particularly valuable to customers whose teeth are tight up against each other. Thus, the name Glide.

Glide itself is an interesting product, but it’s the package that I want to talk about for a minute. The Glide floss package is a single injection molded part designed with a living hinge that allows it to both fold into the deployed configuration, include an integral cap, and to be configured in a way that it can be molded as a single piece, and in a way that the part can easily come out of the mold.

My guess is that the manufacturing cost of this package is a few cents. Although the smooth pebble-like form is unobjectionable, the glide concept really shines not because of its beauty or function, but because of its extreme cost efficiency.

3. Wow Factor

The third characteristic of a great concept is what I call the wow factor. Here’s an example. I have an app on my mobile device called “Picture This.” I was riding my mountain bike this past summer and sat down for a rest. I smelled an interesting minty fragrance, which seemed to be coming from foliage near my feet. I snapped a photo using PictureThis and within seconds the app told me I was looking at Mountain Monardella, also known as mountain coyote mint. Who knew? Picture This has a bunch of nice features including the ability to keep a database of plants previously identified. But, the wow evoked when some image processing algorithm identifies a plant from a snapshot is magic.

The wow factor is valuable for at least two reasons. First in a commercial context, if you have some wow, then you typically also can achieve some intellectual property protection, usually in the form of a patent. This can provide a modest and temporary barrier to competitors replicating your design.

The second reason, and perhaps the more important reason, is that if you’ve got some wow in your concept, then you have something to talk about in the market, and you can get a user excited about the product. In a commercial setting it allows for your product to distinguish itself from the competing alternatives.

4. Aesthetics and Elegance

The fourth and final characteristic of a great concept is aesthetics and elegance. That is, as designers we should strive to create things that are beautiful. I can wax on about the beauty of purely functional objects, but automobiles are perhaps more interesting examples because they embody a complex bundle of function, identity, and meaning. When Volkswagen announced its all electric microbus, it revealed a concept to which a lot of attention had been paid to aesthetics, including a careful and tasteful reflection of the heritage of the original VW van.

OK so those are objectives. We want to create something that meets user needs, can be produced at low cost, has some wow, and is beautiful.

Concepts for Digital Goods

The four elements that make for a great concept are particularly important for physical goods and for services. In both physical goods and services, cost is critically important. However, for digital goods, cost is usually less important.

Furthermore digital goods can often be thought of more as bundles of features than as a single distinctive solution concept. These features can be added and subtracted incrementally over time as the product evolves.

Perhaps in part for these reasons, the development of a great concept tends to receive less attention for digital goods than it does for physical goods or services. Zero-to-one product managers sometimes feel that a software solution concept follows directly from the job to be done and the customer needs, and even if it doesn’t, the solution can be refined over time.

I think this view is a mistake. Digital goods offer almost unlimited flexibility in solution approach, so if anything, a thorough exploration of the solution landscape is even more important in digital goods than it is in physical goods.

Let me give you a few examples of distinctive concepts in digital goods.

Twitter – what’s the concept? A social network organized around the idea of followers in which an individual creates a virtual bulletin board, usually viewable by the public, in which messages of 144 characters or less are posted chronologically. Messages are pushed to followers and appear on a scrollable feed. (Of course many features have been added over the years, including direct messaging, the ability to respond to tweets, the ability to like tweets and so forth, but the original and still essential concept is quite distinct.)

Slack – what’s the concept? SMS/Txt for work, organized around topical channels. The big idea is to consolidate information and discussions into threads by topic to avoid the chaos of email. Again, many additional features have been added over time, including document sharing, emoji responses, push notifications and so forth. But, the big idea remains asynchronous communication for work organized by topic.

Tinder – what’s the concept? A mobile-only dating app focused on photos, in which individuals express interest in a potential partner by swiping an image to the right, and rejecting a potential partner by swiping an image to the left. When and if two parties swipe right on each other, the app declares a match and allows the two parties to start a conversation via text message.

Strava – a GPS-enabled fitness app, originally focused on running, in which an individual’s route and running time are automatically recorded, and then shared with a network of other runners. The route is automatically divided into segments and a leaderboard is established for the fastest times along those segments.

Because these concepts have been so successful, we take them for granted, even assuming that there could only be one way to do things. But, that perception reflects a hindsight bias.

There are a huge number of possible solution concepts for virtually any problem domain. For example, consider the simple task of listening to pre-recorded music using a digital device. What are the different ways that might be done?

One early solution, Apple iTunes, had these key elements. The iTunes store in which you could buy individual songs, originally for USD 1 each. Then, local storage of those songs in a master library on a physical device. Then, the creation of playlists from the master library. That was it.

A very different, and quite revolutionary concept arrived with the service Pandora. With Pandora, a user simply typed a single song or artist into a web-based application and Pandora created a virtual radio station based on other songs that shared the same “music genome” – Pandora’s name for the distinctive musical elements of a song. No need to create playlists. Pandora does it for you, and you can have as many stations as you want for  free, if you are willing to listen to some audio advertisements, or if not, for a single monthly subscription fee.

Then, Spotify came along with an all-you-can-eat subscription service in which you could create playlists from extensive available catalogs, but without actually having to own and keep track of the digital content itself.

Today, YouTube Music is a significant player in the music space. The insight addressed by YouTube is that in many settings people really want the option of viewing video of the artists from live performances or highly produced visuals.

I know some of you are thinking that these different ways of listening to music are now blended together on many platforms. For example, Spotify allows for downloading of files for off-line listening and allows for the use of Pandora-like stations. By the way, I recommend the “dinner chill” station for nice music for dinner parties.

This convergence is a reflection of the massive amount of experimentation and innovation that competitors have engaged in over about two decades at the beginning of this century. At some point preferences of customers became clear, market segments came into focus, and the solution concepts matured and became fairly stable. This is the normal pattern of evolution in an industry.

The maturation of the approach an industry takes to doing a job is another reason concept development may not be emphasized as much as it should be for digital goods. So often the product manager joins the team long after the original solution concept was established. Anyone joining Strava today as a product manager would not likely be doing a zero-to-one design for a new app, but rather would be improving and tuning an existing app. Still, even in this context, the skill of concept development is important. Even if you are working on some small feature within a larger established product context, you should strive for a solution concept that meets needs, is cost efficient, has some wow, and is beautiful.

Concept Development – Basic Approach

The essence of the third diamond in the triple diamond model is another cycle of divergent and convergent thinking. 

Concept generation and selection is essentially a mini tournament of ideas. We’re going to generate a lot of alternatives; a dozen or maybe even a hundred different solution concepts. We’re then going to select from among those in order to find an exceptional concept.  For most people this does not come naturally. The good news is that as with most challenges in life, a little bit of process and practice goes a long way.

Before we get into the mechanics of how to actually do this, I want to emphasize three points.

First, I want to emphasize that concept generation is really hard. It takes much more effort than most people appreciate. I do not want to sugar coat this reality. Here’s an example to illustrate what I mean.

Some of you might have noticed a little stick figure in some of my illustrations. The stick figure is one element of one graphic in a few sessions of one of my courses. There are hundreds of such elements.

But that little stick figure concept is the result of deliberate exploration. I went back through my files and I found this sheet showing more than 100 different alternatives for what that stick figure might look like. I eventually found one that I thought worked quite well. Some of you are rolling your eyes and thinking how can it possibly be worth investing that kind of effort in a stick figure. You could be right.

But, the point I want to make here is that the tiniest design challenge when done well still requires tremendous effort. This is hard work. You need to be prepared to do the hard work to get great outcomes.

As a slight aside, let me make a comment about life and professional success more generally. You should embrace things that are hard, especially when by hard, I really mean just putting in the effort. If you can internalize the idea that great concepts are mostly the result of hard work, while others believe a spark of creative genius is required, then you have a superpower. You can be confident that if you do the work using a solid process, you are going to get better results than everyone else, and all you have to do is show up and do the work.

The second point I want to make about exploration is that we need to be open to ideas that come from anywhere and everywhere. Sometimes it’s even dumb luck that leads to a great design concept.

Here’s an example. I’m the inventor of a product called the Nexride bicycle seat. Let me tell you where the concept came from. A few  years ago I was working on creating a better bicycle seat. As part of the process I was testing out several of the existing non-traditional products. I was out riding one of the saddles that’s essentially a bench-shaped form mounted perpendicular to the direction of travel.

So, I’m out riding about 30 kilometers from home when the clamp that attaches the seat post to the frame breaks. This meant not only that the seat fell down so that it was right up against the frame, but also that it was free to pivot side to side. I considered walking home, but then decided I should try to ride the bike anyway, as that approach would still be faster than walking. To my dismay I discovered that the pivoting action allowed by the lack of a rigid clamp made the saddle much more comfortable. It allowed the bench to get out of the way as my leg extended on the down stroke.

I immediately went home and created a prototype of a pivoting bike seat, and I eventually ended up inventing a new saddle, the Nexride bicycle seat.

I say “invent” but really that concept came from a dumb accident – a broken bolt out on a bike ride. I’m not complaining. In fact,  I’m emphasizing that you need to be open to the possibility of ideas from any source including random occurrences.

Lastly I want to point out that even though we have a process, and I am going to teach you some methods for doing exploration, please understand that concept generation tends to be highly iterative. It’s quite likely that as you generate ideas, the definition of your job to be done will come into better focus. It’s also quite possible that as you proceed to refine a particular concept and build and test prototypes, you’ll have additional ideas for new concepts. That’s normal. Don’t be alarmed. That iteration is fundamental to the way design happens in practice. 

A few years ago I founded a company called Terrapass. We provided a service to offset the environmental footprint of driving a car. Given the complexity of understanding what and how we actually mitigated environmental damage, we settled on a solution concept that was very simple. For one fixed fee, USD 79 per year, we would provide enough carbon dioxide credits to offset the emissions of your car. See, it’s really, really hard to explain the product clearly. Still, what we discovered was that our customer was really interested in the details, and had a deep appetite for understanding  the nuance of the environmental impact of driving. We found that we had to modify our concept, and actually increase complexity by adding a highly customizable emissions calculator to our website. This solution allowed the customer to precisely specify the make and model of their car, the amount of driving they did, and their driving habits. Iteration on the solution concept is usually required in order to achieve great outcomes. 

Ideation process

I’ve mostly talked about the third diamond in generalities. Let’s dive into the details, starting with the divergent part. How can you reliably generate a lot of solution concepts?

The human mind is pretty good at thinking of solution concepts, especially after considering carefully the job to be done and engaging with the customer. So, before getting too fancy, just write down or sketch out any ideas you have from the top of your mind. In my experience, you already have at least three or four ideas. 

Now comes the part that really differentiates expert creators from novices. Just put those ideas aside. They may eventually prove to be the best solution to the job at hand. But, experts know that those ideas are not going away. You’ve already captured them. So, just let them go for now. Move on and see if you can generate another half dozen or more alternatives.

You can use some simple techniques to stimulate your thinking. Here are five that I like.

First, pull from insights. You’ve already invested heavily in the second diamond, understanding the customer, and that effort should have produced a couple of insights. Insights are customer needs that are authentic, non-obvious, and significant. I guarantee you that if you identify an insight, a solution concept will just fall out of your mind.

Let’s try it. My hoped-for new venture 99 Bowls makes and ships frozen prepared lunch foods like soups, chowder, and chili to professionals working from home. In my customer research, I identified the insight that many people strive to tightly control the macro nutrient profile of their food. For example, some want higher fat and lower carbohydrates, and others low fat and high protein. Can you think of any solution concepts for 99 Bowls that would be responsive to that insight? 

Of course you can. Here are a few. How about starting with standard recipes, say for chili (a mexican-inspired spicy soup), but whose ingredients can be adjusted in a custom production process to deliver a pre-specified macro nutrient profile? Want higher fat and lower protein? Increase the amount of cheddar cheese and reduce the amount of ground turkey. Want higher carbohydrates? Substitute corn kernels for the cheddar. Another would be to have a vast assortment of soups, but then to automatically filter the options to those that satisfy the customer’s desired nutrient profile. A third option would be a sort of bento box that assembles different food items – say sliced turkey, pita chips, hummus, and cheese – into a lunch portfolio that satisfies the overall target nutrient profile.

In fact, the whole purpose for finding those insights in the first place is to use them to pull distinctive solution concepts. This technique is the most powerful item in your concept generation tool kit.

A second approach is to apply the decomposition principle, focusing on just one element of the job to be done. You can decompose by customer needs, which is essentially what we do when focusing on an insight, or you can decompose by sequence of user actions or according to different sub-functions within a larger solution. For example, for 99 Bowls we might decompose the overall service into selection, ordering, delivery, and consumption. Now, focus on just one of those functions and consider all the different ways you might do it. For instance, consider delivery. 99Bowls could ship a carton of 12 individual servings that are frozen and placed in insulated packaging. Or, the customer could pick up a month’s supply at a regional refrigerated drop-off point. Or, a single serving could be delivered ready to eat at a pre-specified time each day. Or, the company could locate a compact freezer in apartment complexes and neighborhoods acting as a sort of vending machine for meals that have been pre-purchased. We could follow the same process for the other sub-functions, say selection. Once the decomposed problem has been tackled, pieces that work together can be assembled into complete solution concepts.

In a third approach, consider how an organization with a distinctive approach to product would solve the problem. For example, how would the Japanese household products company Muji implement 99 Bowls? I’m envisioning very tidy and beautiful containers, likely rectangular in shape that stack into a modular storage and shipping solution. The containers are either reusable or returnable. How would Nike do it? Maybe with selections endorsed by famous athletes – say the Michael Jordan meal plan. How would Netflix do it? They would make meal suggestions based on my eating history. You get the idea – take the best elements of the distinctive approaches of other companies and see how they might apply to your challenge.

Fourth, consider analogous problem domains. 99 Bowls is trying to solve the problem of what’s for lunch while working from home. What’s an analogous problem? Maybe the problem of what to watch at home in the evening. How do I solve that problem? I have different channels and platforms like YouTube, Disney, HBO, and Hulu. Maybe I can have different lunch channels, with varied offerings.

Fifth, set a numerical goal. I generally like to use a goal of 10 distinct solution concepts. Over thirty years of teaching product development, I’ve found that the number 10 is challenging, but achievable. If you have identified 10 distinct ways to do a job, you have probably done a decent job of covering the landscape.

All else equal, the easiest way to find a better idea is to generate more ideas. And, the easiest way to generate more ideas is to engage more people. Engage your team. Engage your engineers. Engage your customers. Ask anyone who will listen if they have suggestions or ideas about how to do the job.

One technique I like when working with a team, is to prepare in advance a list of what I call Emergency Stimuli. These are prompts that might dislodge new ideas. Here’s an example of some stimuli for the 99 Bowls challenge.

• What food trends are taking hold in restaurants located around busy office complexes? Might some of those trends be applied in a home delivery service?
• As increasing numbers of professionals work from home, what are the most common complaints about the experience? Might 99 Bowls address some of those pain points?
• What innovations in food science are emerging, but perhaps not yet widely available? Might some of those innovations be incorporated into the 99 Bowls solution.

In my experience, almost any prompt will work to get team members unstuck. Just think of a handful of questions that can nudge people to think differently, and then use those questions when and if the ideation process gets stalled or people complain they are out of ideas.

The divergent portion of the third diamond is all about generating a lot of alternatives. There’s no shortcut, other than perhaps the trick of involving a lot of people, which certainly makes the task easier. Apply the process, do the work, engage a team, and you’ll end up with a rich set of solution concepts.

Harnessing the Power of Individuals and Groups

Some projects are completed by individuals working alone, but more typically you will find yourself in a team. How can you most effectively harness the power of individuals and groups to generate concepts?

The most common organizational practice is to call a meeting and to conduct a brainstorming session. You’ve all done this. You get a group of people around the table. Maybe you have a flip chart and an easel or a whiteboard, and someone facilitates the meeting.

I exaggerate only slightly in saying that this is probably the single worst thing you can do in order to effectively deploy your team.

Let me make an analogy. Imagine that you and your team are on a small plane that crashes on a remote island. Everyone survives but your first task at hand is to find food, water, and shelter – this is the metaphorical equivalent of looking for a great solution concept.

Now imagine two strategies. In the first, the team huddles together in a rugby scrum and you wander around as a group looking at the ground together. That’s the equivalent in organizational life to calling a meeting.

In a second scenario, everyone on the team heads off in different directions, with the mandate to come back and report on what they found after 30 minutes. Then, after sharing information you all go look more carefully in the most promising areas.

Hopefully your intuition is that the second approach will more reliably find the best food, water, and shelter. This same strategy of employing independent parallel exploration is also the best way to engage a group in concept development.

You don’t have to take my word for it. My colleagues Christian Terwiesch, Karan Girotra, and I have tested this idea experimentally. We compared two different approaches to ideation. In what we call the group approach, four people work together for 30 minutes. In a second technique, we call the hybrid approach, those same four people work for 10 minutes alone as individuals independently and in parallel and then those four people work together for 20 minutes exploring the ideas that they generated alone as individuals.

We did this study with 44 individuals divided into 11 groups of 4 and we had them work on exploring for alternatives for two different product design problems.

We found that with the hybrid approach the same 4 individuals could generate about 2 – 1/2 times more ideas if they took the hybrid approach than if they worked together as a group.

Not only that but the ideas they generated were actually better in quality as well. 

We have unambiguous evidence that a hybrid process is better than a group process and that you need to have an individual phase for at least some of your exploration effort. 

It’s very helpful to provide a numerical target for that individual phase. I usually use a goal of 10 ideas per individual.

Lastly, some people find out that it’s very hard in some organizations to actually get people to do their homework –  that is to actually do the assigned work of generating 10 ideas working individually. 

If that’s the case for you, then I recommended you go ahead and call a meeting, which is effective in getting people to allocate some time.  But then after you’ve called the meeting and after you’ve got people together, you ask them to work alone for the first 10 minutes, after which you can proceed to work together as a group.

Just to be sure I’m clear, I want to reiterate that I’m not opposed to working in teams. Rather, you should cherish the value of the team resource and work to deploy it most effectively, by having your team members spend some time working individually and alone before you bring together team members into a group process.

Selection Methods and the Concept Selection Matrix

The third diamond in the triple-diamond model includes a convergence from many solution alternatives to a single plan for going forward. We clearly shouldn’t pick from our alternatives at random. How do we converge?

In most cases, the convergence comprises two steps. First, the team, without the benefit of any external testing, narrows a set of 10 or more solution alternatives to a few, say 2 or 3. Second, some kind of testing with potential customers is used to converge on the best single solution. Here I focus on the first step – screening and selecting internally.

The technique used most widely in practice is multi-attribute utility analysis — which is an overly fancy name for a criteria matrix. Even if you don’t know the technical name, you’ve probably used one of these tables before. In this example I use a google sheet to quickly create the matrix, but any table will do, even a marker on a whiteboard.

Just as an arbitrary convention, I like to use the columns for the different solution alternatives and the rows for the criteria.

A desirable characteristic of a structured selection method is that you can remember, codify, and communicate the logic behind a decision long after it has been made. The selection matrix is self documenting. So, if you do use a whiteboard, remember to snap a photo for archival purposes.

For physical goods, I find it is sometimes nice to draw a little sketch next to the textual description of the concept at the head of each column. You can also use a separate document with illustrations to document in more detail each of the concepts captured by the matrix.

The rows of the matrix are the selection criteria. I like the criteria to be the key customer needs. In this example I’ve shown three needs – quick and easy to use, removes all the ice cream from the container, and forms a nice ball. Almost always there are three additional criteria that apply, and they are cost or some measure of the economic efficiency of delivering the solution, wow, that is how fundamentally interesting and novel is the solution, and elegance and beauty. These criteria map directly to the universally desirable attributes of a solution concept.

Now you just consider the relative performance of each concept relative to the criteria. The convention that I like to use for representing relative performance is a three level scale using a plus, a zero, and a minus.

Note that even though I use the term cost here, I adopt the convention that plus is always better, and minus is always worse, so a plus indicates lower cost.

Once you’ve evaluated all of the concepts relative to all of the other criteria, you can then summarize the net score by adding up plusses and subtracting minuses for each concept.

One positive outcome of the selection process is that it helps the team to realize when elements of one concept might be combined with another, or when concepts are actually quite similar to each other. For instance, as a result of this process, I discovered that concept E was conceptually very similar to concept G, a concept that I ended up pursuing further.

In this example, two concepts really stood out as superior, and so I focused on those two for further development. I often see three concepts that emerge as most promising. Rarely does a team have more than three really compelling concepts based on this internal selection process.

Now those of you who are more right brained have an objection. You argue that we can’t really reduce everything in life to a quantitative evaluation. Instead you need to make a more holistic judgment of the qualities of the concepts.

I hear you on this point, and I think it’s good discipline to see if you can get the concept selection matrix to be consistent with your intuition. That suggests that you’ve been able to capture what’s really behind your intuition, and that will benefit you when you go to communicate your rationale to other people, maybe to the more left brain of the stakeholders on the project.

[As a complete aside, I know remembering what those terms left brain and right brain mean is really hard – they are terrible labels. Here’s the mnemonic device I use. Remember that LEFT is LOGICAL…]

Those of you who are more left brained have your own objection. You argue that not all criteria are equally important and that it’s hard to reflect accurately the relative quality of concepts using just three levels. 

Of course both of these concerns are valid. For this quick selection method to be effective, the criteria need to be roughly equal in importance, and in some cases, a crude three-level quality rating will mask some huge differences in relative quality of concepts. You can of course easily modify the criteria matrix to increase the number of quality levels, say using a  1 to 5 scale, and you can weight the relative importance of the criteria using a percentage weighting scheme or a point system. However, in my experience, if the goal is merely to narrow a set of alternatives to about three, then the simple criteria matrix will work quite well.

Concept Testing 

In the third diamond, we are sort of flying blind. It’s been a while since we engaged with our potential customers. For this reason, we need to do some concept testing.

Let me illustrate why this is so important using a simple example. Imagine you are designing a new hot sauce.  (Have you noticed by the way that I use a lot of food examples? That’s because I love food.)

You can think of any individual as having an ideal point, which is their true preference, say on two dimensions of saltiness and spiciness. When you interview them and observe them, they tell you how much salt and heat they like – maybe they tell you they like it really hot and not very salty. Of course, you as the designer don’t hear them perfectly well, and they are not perfectly accurate in describing what they like. There’s inevitably some imprecision.

Then, you go to the lab and create a product based on what you understand, and there is a further translation error in that execution. By the time, you’ve gone through three phases of interpretation, what you have cooked up and what the customer wants are likely not perfectly aligned. Correcting any such mismatch is not hard. You give them a prototype of your hot sauce and ask them what they think. Yikes, they say, that’s too hot and tastes sort of bland. Hopefully you land pretty close though, and can incrementally refine your solution to hit the target.

Of course, I bet very few of you are designing hot sauce, but the same logic applies to creating a service experience or a piece of software. What the customer tells you, how you understand it, and the fidelity of your engineering process will inevitably result in a mismatch between what the customer actually wants and what you have actually built. Concept testing lets us estimate whether or not you have a good match before you actually develop the product.

There are three common types of concept tests. The first is informal qualitative feedback based on a quite schematic description of the solution concept. For example, this is the very first prototype of the Apple iPod. It was made by Tony Fadell from cardboard covered with a laser printed graphic. I bet it didn’t take more than an hour to build.

You can’t have too much feedback on prototypes. Even showing potential users hand-drawn screens on paper – sometimes called “paper prototypes” – is super helpful in clarifying where the solution concept misses the mark.

In a second type of concept test, you set up a forced choice among a small set of concept alternatives, usually three.

For example, here is a forced choice concept test for three ice cream scoop concepts. The 3 options typically result from an internal concept selection process using a criteria matrix in which 10 original concepts are narrowed to 2 or 3.

You can use this kind of forced choice in lots of different design settings, not necessarily just for overall product concepts. Here’s another example of a forced-choice survey I used in testing three possible names for the environmental services company I co-founded. The name Terrapass was the clear winner and we went with that option.

In a third type of concept test, you ask potential consumers to indicate their purchase intent. Purchase intent is almost always measured using a five-box scale, from definitely would not purchase to definitely would purchase.

Here’s one of the ice cream scoop concepts as it would be used in a purchase-intent survey.

Purchase intent surveys are notoriously imprecise in predicting demand, but they are the best single predictor of consumer acceptance of a new product at the concept phase of development. I believe they are best used for relative comparison of several concepts. In my own research, I have found that you can test up to 50 concepts with a single respondent without too much fatigue, and that you only need a sample of about 15 representative consumers to get a reliable estimate of how potential customers will react to your product.

Of course the way you represent solution concepts to your audience influences their response. For example here’s the same purchase intent survey with the concept illustrated with a photo-realistic rendering. In this case the vibrance of the color is much more evident than with a black-and-white line drawing.

You will probably not have the details of your concept fully worked out when you engage in concept testing, so you will have to just do your best in representing the solution. In my opinion, consistency in the fidelity of the concept descriptions across different concepts is more important than the absolute level of quality of the representation of your concepts.

More Iterative Refinement

If you are very lucky, you will find that the concept you select (1) meets the customer needs, (2) is cost efficient, (3) evokes the “wow” response, and (4) exhibits beauty and elegance. More likely, significant iterative refinement remains as you put prototypes in front of potential customers and refine your solution. That’s normal. Hopefully, however, the results of a deliberate concept development process get you close to the target and a process of incremental improvement will allow you to hit the bullseye.

Notes

Karl T. Ulrich, Steven D. Eppinger, and Maria C. Yang. 2020. Product Design and Development. McGraw-Hill. New York.

Laura Kornish and Karl T. Ulrich. 2014. The Importance of the Raw Idea in Innovation: Testing the Sow’s Ear Hypothesis. J. Marketing Research.

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