Hi folks!! This blog will help you to understand the Null hypothesis & Alternative hypothesis.
First, we need to understand what is Null Hypothesis, why it is used & Where it is used.
Null Hypothesis – It is denoted as H0 and is generally assumed to be true.
Let us understand it with an example. Suppose a person (say X) has committed a murder and Police has arrested him and taken to the court.
In the court there is a system of proofing of suspect and in above example, Mr X is suspected.
Here, there will be two statements: – one will be null hypothesis and other one alternative hypothesis.
X’s advocate will put a statement that “Mr. X person is not a murderer”.
So in this case Mr. X not being a murderer is called Null hypothesis H0 and then police will put statement that “Mr. X person is a murderer” and this statement is considered as Alternate hypothesis, which is denoted as H1
So in above example
Null Hypothesis (H0)= “Mr. X is not a murderer”
Alternate Hypothesis (H1) = “Mr. X is a murderer”
H0 + H1 should be mutually exclusive (nothing common) and collectively exhaustive (all possible outcomes are covered).
Lets understand it with some more examples.
H0 – Average car tyre life is = 500 Km, H1 – Average car tyre life is ≠ 500 Km
Ho – Average content of toothpaste = 250 gm, H1 – average content of toothpaste ≠250gm
H0 – Customers are more satisfied now H1 – Customers are less or same satisfied.
H0 – Amazon delivers faster than flipkart H1 – Amazon delivers slower or same.
How to test a claim?
The lower and upper critical values are computed from sample size and the risk assumed of making a wrong conclusion (using values from t or Z table).
Null hypothesis is Rejected or Not Rejected.
It is never accepted, since the decision is based on a sample and not the population.