The Assumption

Identifying assumptions help you de-risk in your product by uncovering what might make your product fail and addressing that first.

An assumption is a statement you are making about your product that is accepted as true without evidence. An assumption can take form as a belief about your audience, a recognition of a business necessity, a projection about market size, and many other things.

A lean experiment should start with the assumption. You will want to validate/invalidate the riskiest assumptions first - the ones that if are invalidated, the product might suffer or fail.

Prioritizing Assumptions

Prioritizing assumptions isn't always easy. I find that rating some questions about an assumption helps me identify the level of risk associated with it. Assign a 2 (for Yes) a 1 (for Maybe) and a 0 (for No). The highest total is most likely your riskiest assumption.

Assumption Example One

Let's pretend we have a product intended to reduce the energy usage in a building by pitting tenants against each other in a competition. Our products allows tenants to see the energy usage of each apartment. The lowest energy consumer gets bragging rights. Let's look at two assumptions and score them:

Tenants are willing to share their energy usage with their neighbors. [1]

Competition will drive change to reduce energy consumption. [7]

Knowing that competition actually will drive change is by far the most important idea to validate before moving forward. Without this, we don't have a product.

Assumption Example Two

Let's imagine we are at a later stage with the app where people are using it, but we aren't seeing a significant reduction in energy usage. Let's look at two assumptions and score them:

People don't know how to reduce their energy usage. [4]

People don't understand the metric we use to compare them. [2]

These two score closely. The main difference is the risk we run of not solving for the first assumption. If people don't know how to reduce their energy usage, then we can never hit our goal of energy reduction and our product fails.


Identifying assumptions help you de-risk in your product. Its best to test the riskiest assumptions first. Prioritizing assumptions is not always easy. I have found the rating these questions about an assumption helpful, but if you don't feel confident that the scoring is accurate enough, I urge you to dig deeper until you have the confidence that you have identified the next riskiest assumption.