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Chapter 9 Notes (1)

Chapter 9 Notes (1) - Chapter 9 Statistical Inference...

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Unformatted text preview: Chapter 9: Statistical Inference: Significance Tests About Hypotheses Significance Test: A significance test is a method of using data to summarize the evidence about a hypothesis. A significance test about a hypothesis has five steps. 1) Assumptions 2) Hypotheses 3) Test Statistic 4) P-value 5) Conclusion Step 1 : — > A (significance) test assumes that the data production used randomization > Other assumptions may include: 0 Assumptions about the sample size or about the shape of the population distribution Step 2 : m > A hypothesis is a statement about a population, usually of the form that a certain parameter takes a particular numerical value or falls in a certain range of values > The main goal in many research studies is to check whether the data support certain hypotheses > Each significance test has two hypotheses: * 0 The null hypothesis is a statement that the parameter takes a particular value. It has a single u_n parameter value. The symbol H denotes null hypothesis. This always has equality .- sign. 0 Ex: Ho: p = 0.72 Ho: u = 42.3 *0 The alternative hypothesis states that the parameter falls in some alternative range of values. The ' symbol H denotes alternative hypothesis. The alternative hypothesis should express what the a researcher hopes to show. This always has one of “>”, “<”, or “¢” signs. Ex: Ha: p < 0.47 Ha: u ¢ 42 Ha: n > 3.45 .30 The hypotheses should be formulated before viewing or analyzing the data! )K Step 3: m > A test statistic describes how 'far the point estimate falls from the parameter value given in the null hypothesis > We use the test statistic to assess the evidence against the null hypothesis by giving a probability, the P-Value. Step 4: m. mm.“ “mm"- 3 Sampling taxman»: > To interpret a test statistic value, we use a probability summary of a“..- 1‘3““ ....._..5 the evidence against the null hypothesis, H 0 0 First, we presume that H is true 0 0 Next, we consider the sampling distribution from which the test statistic comes 0 We summarize how far out in the tail of this sampling distribution the test statistic falls > We summarize how far out in the tail the test statistic falls by the tail probability of that value and values even more extreme . 0 This probability is called a P-value as...“ ____ 0 The smaller the P-value, the stronger the evidence is against H 0 0 The P-value is the probability that the test statistic equals the observed value or a value even more extreme ...
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