Hypothesis – Null and Alternate

Case 1: Null Hypothesis
Among the two phenomena taken under the consideration the null hypothesis is the statement which always denotes that there is no relationship exists between them. The null hypothesis can be accepted or rejected upon verification.
The term null hypothesis is usually denoted as Ho. The term null hypothesis indirectly denotes that the person usually tries to nullify it. So now you can raise the question that instead of having the null hypothesis we can only have an alternate hypothesis. 


Why both the null and alternate hypothesis?
It is usually for anyone to make mistakes, but including both the null and the alternate hypothesis is the safety measures to avoid flaws.

Let us consider the facts,
H0 =   Let us consider the world to be flat.
Ha = The world is round.
Many scientists like Copernicus never simply stated that the world is round. If they simply said this alone many people would not have believed it. But they disproved the null hypothesis with their theories and rejected it.

How to take the null hypothesis from the statements in statistics?
To take out the null and alternate hypothesis from the problem break the problem into many simple steps.
Example : A person has a wound in his hand, the person needs to go to doctor three times in a week to get healed within two weeks, but he goes for only two times which may take longer recovery time. Prove?
Always remember the null hypothesis should be disproved.
So here H0 = person will get recovered in two weeks.
             Ha = recovery time will be greater than two weeks.
Now take the efforts to disprove H0 and accept Ha thus the problem is solved

Null hypothesis based on the P–value 
When the p-value is less than the test value, then the null hypothesis is rejected so the test is significant. But when p-value is greater than the test value null hypothesis is accepted thus the results obtained are not significant.
If we say reject the null hypothesis it does not mean than it is not true the meaning is that there is no proper evidence to prove it.

Case 2: Alternative Hypothesis
The alternative hypothesis is usually a statement that describes the relationship that exists between two consideration. It is usually represented as H1 or Ha.

Why alternative hypothesis is important?
The alternative hypothesis is important that it determines the relationship between two considerations and the study conducted is correct and results are relevant.

Types of Alternative Hypothesis

  • One-sided alternative hypothesis
  • Two-sided alternative hypothesis

In one-sided alternative hypothesis parameter usually differs in only one direction but whereas in two-sided hypothesis differences are seen in both the direction.
Let me explain the alternative hypothesis with one more example.
The researcher assumes the weight-bearing capacity of the machine as more than 10 kg. In these cases the hypothesis is,
H0 = Weight bearing capacity is equal to 10 kg.
Ha = Weight bearing capacity is more than 10 kg.

Comparison between null and the alternative hypothesis

Comparison BasisNull HypothesisAlternative Hypothesis
Mathematical ExpressionIt is usually denoted by the “equals to” sign.It is usually denoted by greater than or less than sign.
ProgressUsually, the researcher tries to disprove it.People find all the possible way to prove this.
SignificanceIf the null hypothesis is accepted the results of the study are found to be insignificant.If alternative hypothesis is accepted the results of the study are significant.


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