# Hypothesis Testing:

### What is hypothesis testing?

Hypothesis testing is a statistical tool or a type of statistical inference which is used to draw conclusions from sample and test whether the assumptions are true for the whole population.

### Null Hypothesis and Alternate hypothesis:

Null Hypothesis and Alternate hypothesis are opposite to each other and each one proves the other is wrong.

#### Null Hypothesis (H0):

It is a well established fact or claim.

Example: There is no relationship between the age and weight

#### Alternate hypothesis (Ha):

You are bringing another claim and proving already established fact is not true.

Example: There is a relationship between the age and weight

### Types of Hypothesis Testing:

#### Z test:

Z test is a statistical test which is used for the data which follows normal distribution. This can be used when the standard deviation and the variance are known, and the number of data is 30 or more. It checks whether the mean of the two populations are same.

#### T test:

T test is used to calculate mean of one or two populations. It checks whether the mean of one population is equal to the known mean or the mean of two populations are same or different. It is not used for multiple groups or populations.

#### Chi- Square test:

Chi square test is used to calculate the difference between the observed value and the expected value of the categorical values of two populations.

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