Hypothesis Testing: An Intuitive Explanation

Learn the step-by-step breakdown of hypothesis testing.

Renu Khandelwal
7 min readDec 26, 2021


How do the pharmaceutical companies check if their current vaccine is effective against the new COVID variant?

They first start with a hypothesis.

Hypothesis is a premise, a claim or an educated guess, based on prior knowledge and observation.

So how do we test if our claim is statistically valid?

The plausibility of a hypothesis is accessed by employing Hypothesis testing. Hypothesis testing is performed by using random sample data coming from a larger population.

A hypothesis test is a test between two competing hypothesis, a Null hypothesis versus an Alternative hypothesis

What is the Null and Alternative Hypothesis?

The Null hypothesis is default or the status quo for a parameter or can be the equality between population parameters.

The Alternative hypothesis is the claim to be tested and always mutually exclusive to the Null hypothesis, a mathematical opposite to the null hypothesis. The alternative hypothesis challenges the Null hypothesis. The Alternative hypothesis is also referred to as the Research hypothesis as it is the claim the researcher wants to establish or find evidence to support.

In our example above, the null hypothesis will reflect a conservative position of no change or no difference compared to baseline. In contrast, the alternative hypothesis wants to establish that the current vaccine has an impact on the new COVID variant.

Specifying null and alternative hypothesis

Null hypothesis: current vaccines have less than 50% efficacy against the new mutant

Alternative hypothesis: current vaccines have more than 50% efficacy against the new mutant

How do we test the hypothesis?

To test the hypothesis, we need to collect sample data representing the population of interest we are studying. A good sample data should have a good representation of the size and variation of the underlying population.

To prove the hypothesis statistically, calculate the test statistics from the sample data to decide if we need to reject the null…



Renu Khandelwal

A Technology Enthusiast who constantly seeks out new challenges by exploring cutting-edge technologies to make the world a better place!