What Null hypothesis is
Null hypothesis is a statement that is assumed to be true and serves as a starting point for statistical testing. It is used to assess the plausibility of an alternative hypothesis.
The steps of null hypothesis testing are as follows:
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Formulate the null hypothesis. This is the hypothesis that is assumed to be true and serves as the starting point for the test.
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Formulate the alternative hypothesis. This is the hypothesis that is being tested and is the opposite of the null hypothesis.
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Collect the data. This involves gathering the data necessary to test the hypothesis.
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Analyze the data. This involves using a statistical test to analyze the data and determine whether the null or alternative hypothesis is supported.
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Draw conclusions. After analyzing the data, a conclusion can be drawn about which hypothesis is more likely to be true.
Examples
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A pharmaceutical company claims that their new drug is more effective than a placebo at treating a certain medical condition. The null hypothesis would be that there is no significant difference between the drug and the placebo.
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A researcher claims that a new educational program significantly improves math test scores for students. The null hypothesis would be that the program does not have a significant effect on math test scores.
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A survey shows that the majority of people prefer a certain brand of cereal. The null hypothesis would be that there is no significant difference in preference between the brand and other cereals.