STAT 2040 Lecture Notes - Lecture 8: Null Hypothesis, Simple Random Sample, Random Variable
27 Feb 2018
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Chapter 9: hypothesis tests (tests of significance: 9. 1: introduction, there are two main types of statistical inference procedures: confidence intervals and hypothesis tests. Formulating a null hypothesis (h0) and an alternative hypothesis (ha). These hypotheses are based on the research question of interest, and not on the observed sample data: choosing and calculating an appropriate test statistic. So, if the null hypothesis is true the observed value of the test statistic is a randomly sampled value from the standard normal distribution. If there is a pre-specified significance level alpha, then the evidence against h0 is statistically significant at the alpha level of significance if: p-value is less than or equal to alpha. If n > 40 the t procedures perform well in most practical situations. If 15 < n < 40 the t procedures often perform reasonable well, but the presence of outliers or strong skewness can cause problems.
