# How to find the null hypothesis and alternative hypothesis

## Null Hypothesis and Alternative Hypothesis

An Easy Rule to Setting Up the Null & Alternate Hypotheses! - Statistics Help

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By Deborah J. When you set up a hypothesis test to determine the validity of a statistical claim, you need to define both a null hypothesis and an alternative hypothesis. Typically in a hypothesis test, the claim being made is about a population parameter one number that characterizes the entire population. Because parameters tend to be unknown quantities, everyone wants to make claims about what their values may be. Researchers often challenge claims about population parameters.

Generally to understand some characteristic of the general population we take a random sample and study the corresponding property of the sample. We then determine whether any conclusions we reach about the sample are representative of the population. This is done by choosing an estimator function for the characteristic of the population we want to study and then applying this function to the sample to obtain an estimate. By using the appropriate statistical test we then determine whether this estimate is based solely on chance. The hypothesis that the estimate is based solely on chance is called the null hypothesis. Thus, the null hypothesis is true if the observed data in the sample do not differ from what would be expected on the basis of chance alone. The complement of the null hypothesis is called the alternative hypothesis.

If you're seeing this message, it means we're having trouble loading external resources on our website. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Idea behind hypothesis testing. Examples of null and alternative hypotheses. Practice: Writing null and alternative hypotheses. P-values and significance tests.

The null and alternative hypotheses are two mutually exclusive statements about a population. A hypothesis test uses sample data to determine whether to reject the null hypothesis. About the null and alternative hypotheses Learn more about Minitab Null hypothesis H 0 The null hypothesis states that a population parameter such as the mean, the standard deviation, and so on is equal to a hypothesized value. The null hypothesis is often an initial claim that is based on previous analyses or specialized knowledge. Alternative Hypothesis H 1 The alternative hypothesis states that a population parameter is smaller, greater, or different than the hypothesized value in the null hypothesis.

Hypothesis testing involves the careful construction of two statements: the null hypothesis and the alternative hypothesis. These hypotheses can look very similar but are actually different. How do we know which hypothesis is the null and which one is the alternative? We will see that there are a few ways to tell the difference. The null hypothesis reflects that there will be no observed effect in our experiment. In a mathematical formulation of the null hypothesis, there will typically be an equal sign.

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