ENVS278 Chapter Notes - Chapter 18: Standard Deviation, Effect Size, Null Hypothesis
8 Oct 2016
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The appropriate null hypothesis and the value for the null hypothesis arise directly from the context of the problem. Think about why the study is being done and what we want to learn from the test, the null hypothesis is that the situation has remained unchanged. The alternative hypothesis is what we hope to prove. Example: a drug company wants to prove that a new drug is effective. The null hypothesis might state that those who take the drug and those who take the placebo recover is the same proportion. The alternative hypothesis would be that the drug cures a higher proportion of patients. Although null hypothesis usually means zero or none, you cannot automatically interpret it to be zero. If the data supports your claim (the alternative hypothesis), then p-value will be small and you can reject the null hypothesis and will be left with what you want to show. A p-value is actually a conditional probability.
