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Unformatted text preview: Chapter 8: Introduction to Hypothesis Testing Monday, September 26, 2011 Inferential Tests: The ztest and the onesample ttest Allow you to make probability statements about whether a sample of scores has a certain population mean. Examples: Can people accurately estimate the passage of time? Are perceptions of risk accurate? Do single mothers earn similar salaries to all adults? Monday, September 26, 2011 Calculating test statistics • A test statistic is a value you compute from descriptive statistics • e.g., mean, standard deviation, standard error of the mean, N X  μ z = σ X X  μ t = s X The “ztest” The “one sample ttest” Monday, September 26, 2011 Test statistics are compared to Critical Values • the computed ztest statistic is called “z observed” or z obs • z crit is found in Table C.1 • the computed ttest statistic is called “t observed” or t obs • t crit is found in Table C.2 Monday, September 26, 2011 Do single mothers’ salaries (your sample) differ from the average American adult salary (the population in question)? DV = annual gross income Descriptive statistics for the sample and population: Single mothers (X = 32000, s = 6500, N=200) All U.S. Adults ( μ = 34000, σ = 6100) Example #1 Monday, September 26, 2011 Five Steps in Hypothesis Testing *Before beginning, read the problem and select a test statistic (1) Formulate statistical hypotheses (2) Locate the rejection region(s) in the sampling distribution of...
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 Spring '10
 DAMARE
 Statistics, Statistical hypothesis testing, rejection region

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