Hypothesis Testing Using a Single Sample Z-Test On Aggression Levels

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Hypothesis Testing Using a Single Sample Z - Test on Aggression Levels Exercise 8: Single sample z - test As preparation for this exercise, you are strongly advised do the Time to Practice exercise 1, 2, 3 and 4 in chapter 10, and check your work against the correct answers in the text. Test the hypothesis that the subjects in the data set sample are more or less aggressive before the intervention than a comparison population which has an aggression mean of 5 and a standard deviation of 1. Indicate the following steps: 1. State the null and research hypotheses: Null hypothesis : μ = 5 Research (Alternative) Hypothesis : μ ≠ 5 (claim) 2. Set the level of significance, or Type 1 error, and explain what it means. Traditionally we take 0.05 as level of significance. The level of significance is the probability of incorrectly rejecting the null hypothesis in favor of the alternative hypothesis (the claim in this case) 3. Select the appropriate test statistic, and explain why it is appropriate. Describe the formula (10.1) for the statistic and what it means. The test statistic is a one sample z - test for a mean : the formula used is : 𝑧 = 𝑥 − 𝜇 𝜎 √ 𝑛 4. Compute the test statistic to get the ‘obtained value’. By using the Excel data on pre - aggression data we found : x = 5.75, n = 12 and 𝜎 = 2 . 60 Therefore : 𝑧 = 5 . 75 − 5 2 . 60 √ 12 = 1 . 00
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