Understanding Null And Alternative Hypothesis With Example

Hypothesis testing gives us a statistical idea whether our claim is right. It is very useful in a way to prove whether the result was a mere coincidence.

Example:

Here we would try to understand about hypothesis testing from a real life example. Let us imagine a scenario where the Oxford University claims that the vaccine developed by them can cure 90% patient in the world. But W.H.O believes that this is a bogus claim. From these two statements we shall try to form the NULL and Alternative hypothesis.

Null Hypothesis:

Here the claim by the university is that the vaccine cures 90% patients. So we want to test this statement. Hence it is the null hypothesis. We are going to accept it unless there is a strong evidence against it. Traditionally we represent Null Hypothesis using the symbol H₀. So we have to assume Null Hypothesis is 0.9 which we can write as p=0.9.

Alternate Hypothesis:

In the first paragraph we mentioned that WHO believes that this vaccine won’t be effective. So the claim that we wanted to test was the NULL hypothesis as we mentioned before. Now that WHO believes that it won’t be effective so we can state that the alternative hypothesis is H₁: P < 0.9. This expression is very much suited to WHO’s statement where it says that Null hypothesis would be rejected if less than 90% people are cured. We would accept the alternate hypothesis if we are able to reject the Null hypothesis.

What’s Next:

In the previous steps we determined what are the subjects we want to test. The next step is to find a good test statistic which we can use to test the hypothesis. In the next article we would see how the hypothesis testing is done.

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