Assumption Vs Hypothesis in Lean Start-up practice

Assumption Vs Hypothesis in Lean Start-up practice

Decision Time

In science hypothesis and assumption are concepts that are similar in nature and are used commonly in research and experiments.

So what is Hypothesis?

Something that has yet not been proved to classify as a theory but believed to be true by the researcher is labeled as a hypothesis. A hypothesis is merely a proposition that is presented or put forward by a scientist to explain a natural phenomenon. It does not become a theory until it is proved and tested under different conditions and circumstances. At best, it is an assumption that has been made working.

What is Assumption?

An assumption is any statement that is believed to be true. Many times, people pay dearly when they jump to conclusions based upon their assumptions. Thinking about the feelings of others is merely assumption as there is no way to tell what a person is thinking or feeling.

What is the difference between a Hypothesis and Assumption?

• Hypothesis is an argument put forward to explain a phenomenon or sets of phenomena

• Hypothesis is not a theory until it has been proved and verified under different circumstances

• Anything taken for granted is an assumption, and a hypothesis is at best a working assumption

• Hypothesis is a theory in waiting as it can be called theory only after verification


Webster’s Dictionary presents the following definitions for these terms:

  • Fact – the assertion or statement of a thing done or existing;
  • Assumption – the act of taking for granted, or supposing a thing without proof;
  • Observation – the act or the faculty of observing or taking notice; the act of seeing, or of fixing the mind upon, anything.
  • Hypothesis – something not proved, but assumed for the purpose of argument, or to account for a fact or an occurrence

So what interpretation the Lean Start-up practice is suggesting?

In his article “Difference Between a Hypothesis and an Assumption“, Sean Murphy argues that hypothesis is what is being tested explicitly by an experiment. An assumption is tested implicitly. By making your assumptions as well as your hypotheses explicit you increase the clarity of your approach and the chance for learning.

The two things that can trip you up most often is an unconscious assumption that masks a problem with your hypothesis or an unconscious bias in who you are testing the value hypothesis on.


The two most important assumptions entrepreneurs make are what I call the value hypothesis and the growth hypothesis. The value hypothesis tests whether a product or service really delivers value to customers once they are using it.

The growth hypothesis tests how new customers will discover a product or service.

As soon as we formulate a hypothesis that we want to test, the product development team should be engineered to design and run this experiment as quickly as possible, using the smallest batch size that will get the job done.

Here is the process suggested by Steve Blank:


Personally my interpretation on the difference between assumption and hypothesis is the following:

Assumption is a general feeling about a business problem. In order to test if it’s true or not one should develop a sound hypothesis (one or many) relevant to the assumption and the business problem.

For example:

Let’s say that you like to develop ice-cream business.

One of the assumptions may be that most kids like to eat ice-cream.

However, you like to develop this business in your city X. So in this case, you might like to test the following hypothesis: More than 50% of the children in city X eat ice-cream.

Next step is to come-up with a good test to validate this assumption.


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