# Hypothesis Testing: An Intuitive Explanation

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

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*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…