Idea Validation: Product

Guerilla User Testing

Conduct brief user tests in the wild with complete strangers

Illustration of Guerilla User Testing
Run a Guerilla User Testing play

Also called: Hallway Usability Testing

Difficulty: Easy

Evidence strength

Relevant metrics: Usability, Customer feedback

Validates: Feasibility

How: Conduct 3-5 brief usability or product tests no longer than 15 minutes with users merely looking like somebody from your target audience to reveal valuable insights from outside perspectives. Approach a stranger, ask if they'd like to participate, give them a few tasks to do, observe their interactions, and ask about their experience.

Why: Some would argue that testing on more than 3-5 users is a waste of time and resources – some the opposite. Regardless of what is considered correct, testing on zero users yields zero insights. Conducting just a few small user tests with random lookalike users can quickly reveal valuable insights in a matter of hours rather than days and will as such allow faster design iterations.

This experiment is part of the Validation Patterns printed card deck

A collection of 60 product experiments that will validate your idea in a matter of days, not months. They are regularly used by product builders at companies like Google, Facebook, Dropbox, and Amazon.

Get your deck!

Before the experiment

The first thing to do when planning any kind of test or experiment, is to figure out what you want to test. To make critical assumptions explicit, fill out an experiment sheet as you prepare your test. We created a sample sheet for you to get started. Download the Experiment Sheet.

Elaborate usability tests are a waste of resources

As early as in year 2000, Jakob Nielsen claimed that “The best results come from testing no more than 5 users and running as many small tests as you can afford.” The reason being that the number of new usability problems found and learning obtained drastically decline the more tests you conduct to a point where it isn’t of any significance. He claims that after the fifth user, you are practically wasting your time by observing the same findings repeatedly, but not learning anything new.

There are no facts inside your building

Go outside. Go to locations where you will find target users and ask them to use your prototype for a quick minute or two. The guerilla approach to usability testing tries to remove barriers and challenges related to scheduling, papwerwork and setup. Instead the focus is to get out of the building to find real potential users in the wild.

After the experiment

To make sure you move forward, it is a good idea to systematically record your the insights you learned and what actions or decisions follow. We created a sample Learning Sheet, that will help you capture insights in the process of turning your product ideas successful. Download the Learning Sheet.


Discount testing

In his seminal 1994 academic article, Jakob Nielsen demonstrated that using discount usability testing methods yielded much better cost-benefit ratios over more expensive lab-based versions and that the point of diminishing returns on how many tests to carry out was around 3-5.

Source: Guerrilla HCI: Using Discount Usability Engineering to Penetrate the Intimidation Barrier

Want to learn more?

Receive a hand picked list of the best reads on building products that matter every week. Curated by Anders Toxboe. Published every Tuesday.

No spam! Unsubscribe with a single click at any time.

Set goals

Convert empathy to clarity by refining insights into problem definitions

Ice Breakers

Relieve initial group awkwardness and establish a safe space

Community events
Product Loop

Product Loop provides an opportunity for Product professionals and their peers to exchange ideas and experiences about Product Design, Development and Management, Business Modelling, Metrics, User Experience and all the other things that get us excited.

Join our community

Made with in Copenhagen, Denmark

Want to learn more about about good product development, then browse our product playbooks.