What is a hypothesis?

A hypothesis is an educated guess (often about the cause of a problem) that hasn’t been confirmed yet. Think of it as a possible explanation that needs to be tested.

A scientific hypothesis refers to a hypothesis that will be proven using the scientific method (a series of steps to investigate a claim using measurable evidence). A key element of a scientific hypothesis is that it can be proven wrong (meaning it’s falsifiable).

How do you set up a hypothesis?

There are a couple characteristics of a good hypothesis:

  • it involves an independent variable and a dependent variable,
  • it’s testable, and
  • it’s falsifiable.

The independent variable is the cause (the aspect can be changed or controlled) and the dependent variable is the effect (the testable outcome).

A hypothesis is usually written as a statement describing a possible explanation that connects those two variables (see examples below).

A helpful way of ensuring you have a falsifiable hypothesis is to drop your variables in this question: “If [independent variable/cause] occurs, will [dependent variable/effect] be true or false?”

What is an example of a hypothesis?

Some examples of hypothesis might be:

  • A simplified form generates more trial sign ups than a detailed form.
  • Pricing package A is more popular with customers than pricing package B.
  • The holidays negatively impact our weekly average website sessions.

What is a null hypothesis?

There are several different types of hypothesis (e.g. simple, complex, statistical, empirical, etc.), but an important type to know is a null hypothesis. This type of hypothesis states that there is no significant relationship between the two variables. The symbol for a null hypothesis is HO.

Basically, a null hypothesis claims the opposite of a typical hypothesis. The purpose of a null hypothesis is to allow the experiment results to contradict the hypothesis, thus proving that there is in fact a relationship between the two variables.

Null hypothesis example

The following null hypotheses are the inverse of the hypotheses mentioned above.

  • On average, there is no difference in the amount of sign ups generated between the simplified form and the detailed form.
  • Pricing packages A and B are equally popular with customers.
  • The holidays make no significant impact on our weekly average website sessions.

Additional resources for learning more about hypotheses