MATH 10041 Chapter Notes - Chapter 10: Null Hypothesis, Sampling Distribution
8 Apr 2019
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10. 1: the basic ingredients for testing with categorical variables. Two-way table: a summary table that displays frequencies for the outcomes. Expected counts: the numbers of observations we would see in each cell of the summary table if the null hypotheses were true. Chi-square statistic: a statistic that measures the amount that our expected counts differ from our observed counts. Degrees of freedom: the shape of the chi-square distribution depends on this parameter. *if the data conform to the null hypothesis, then the value of the chi-square statistic will be small. For this reason, large values of the chi-square statistic make us suspicious of the null hypothesis. *the chi-square distribution provides a good approximation to the sampling distribution of the chi-square statistic only if the sample size is large. For many applications, the sample size is large enough if each expected count is 5 or higher.
