In mathematics, Statistics deals with the study of research and surveys on the numerical data. For taking surveys, we have to define the hypothesis. Generally, there are two types of hypothesis. One is a **null hypothesis** and another is an alternate hypothesis.

In probability and statistics, the null hypothesis is a comprehensive statement or default status that there is zero happening or nothing happening. For example, there is no connection among groups or no association between two measured events. It is generally assumed here that the hypothesis is true until any other proof has been brought into the light to deny the hypothesis. Let us learn more here with definition, symbol, principle, types and example, in this article.

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## Null Hypothesis Definition

The **null hypothesis** is a kind of hypothesis which explains the population parameter whose purpose is to test the validity of the given experimental data. This hypothesis either rejected or not rejected based on the viability of the given population or sample. In other words, the null hypothesis is a hypothesis in which the sample observations results from the chance. It is said to be a statement in which the surveyors wants to examine the data. It is denoted by H_{0}.

Whereas the **alternate hypothesis** expresses the observations determined by the non-random cause. It is represented by H_{1 }or H_{a}.

### Null Hypothesis Symbol

In statistics, the null hypothesis is usually denoted by letter H with subscript ‘0’ (zero), such that H_{0}. It is pronounced as H-null or H-zero or H-nought.

## Null Hypothesis Principle

The principle followed for null hypothesis testing is collecting the data and determining the chances of a given set of data during the study on some random sample, assuming that the null hypothesis is true. In case if the given data does not face the expected null hypothesis, then the outcome will be quite weaker and they conclude by saying that the given set of data does not provide strong evidence against the null hypothesis because of insufficient evidence. Finally, the researchers tend to reject that.

## Types of Null Hypothesis

There are different types of hypothesis. They are:

**Simple Hypothesis**

It completely specifies the population distribution. In this method, the sampling distribution is the function of the sample size.

**Composite Hypothesis **

The composite hypothesis is one that does not completely specify the population distribution.

**Exact Hypothesis**

Exact hypothesis defines the exact value of the parameter. For example μ= 50

**Inexact Hypothesis**

This type of hypothesis does not define the exact value of the parameter. But it denotes a specific range or interval. For example 45< μ <60

### Null Hypothesis Rejection

Sometimes the null hypothesis is rejected too. If this hypothesis is rejected means, that research could be invalid. Many researchers will neglect this hypothesis as it is merely opposite to the alternate hypothesis. It is a better practice to create a hypothesis and test it. The goal of researchers is not to reject the hypothesis. But is evidence that a perfect statistical model is always associated with the failure to reject the null hypothesis.

### How do you find the null hypothesis?

The null hypothesis says there is no correlation between the measured event (the dependent variable) and the independent variable. We don’t have to believe that the null hypothesis is true to test it. On the contrast, you will possibly assume that there is a connection between a set of variables ( dependent and independent).

### Examples of Null Hypothesis

If a medicine reduces the risk of cardiac stroke, then the null hypothesis should be “ the medicine does not reduce the chance of cardiac stroke. This testing can be performed by the administration of a drug to a certain group of people in a controlled way. If the survey shows that there is a significant change in the people, then the hypothesis is rejected.

Few more examples are:

**1). Are there is 100% chance of getting affected by dengue?**

Ans: There could be chances of getting affected by dengue but not 100%.

**2). Do teenagers are using mobile phones more than adults to access the internet?**

Ans: Age has no limit on using mobile phones to access the internet.

**3). Does having apple daily will not cause fever?**

Ans: Having apple daily does not assure of not having fever, but increases the immunity to fight against such diseases.

**4). Do the children more good in doing mathematical calculations than adults?**

Ans: Age has no effect on Mathematical skills.