Introduction

Most product ideas fail because teams guess too much and test too little. Assumption testing helps avoid that by checking ideas fast.

What's the problem it solves?

Many teams build products based on guesses. They assume users will want something or that it will work, but they don’t test those guesses. This wastes time, money, and effort. Assumption testing helps teams spot what might go wrong early-before they waste time building the wrong thing.

Quick Summary

Assumption testing is the act of checking the smaller ideas that your big product idea is built on. Instead of building a full product and hoping it works, teams should test one belief at a time-like whether users want to share an article or if they’ll understand how to use a feature. These small tests give quick answers and help teams fix mistakes early.

There are five kinds of assumptions: whether people want it, whether it helps the business, whether it can be built, whether people can use it, and whether it’s okay to do. Testing doesn’t need to be fancy. You can use a fake mockup, a short survey, a bit of data, or a simple tech check. The goal is to test quickly and learn before wasting time. Not every assumption must be tested-only the ones that can break your whole idea if they’re wrong.

Good teams don’t wait to test until something’s built. They test ideas before writing code, and they keep testing even after launching. If a test fails, they adjust the idea. If it passes, they keep going. The point isn’t to be perfect right away, but to keep learning and improving with every test.

Key Takeaways from the Article

• Assumption testing helps teams avoid guessing and failing later.
• An assumption is a belief that needs to be true for an idea to work.
• Only test the risky assumptions-the ones that could ruin the idea.
• Tests should be quick: use a mockup, short survey, data, or mini tech task.
• Test before you build. Don’t wait to learn something is broken.
• Five kinds of assumptions: want, business value, buildability, usability, and ethics.
• Tools like Figma, Typeform, or Mixpanel can help with tests.
• Write each assumption clearly, so it’s easy to test.
• Keep track of what you tested, what happened, and what you learned.
• Even if you're busy, start small. A 1-hour test is better than nothing.
• Testing works for both new and old products-it’s always useful.

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