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W3 How Do We Recognize Chi-Square

W3 How Do We Recognize Chi-Square - very likely use...

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How Do We Recognize Chi-Square? The value of chi-square is that it looks at how well an observed set of data fits an expected set of data. ..and this is called the "goodness-of-fit-test." We note that this is different than the z and t test statistics which tests one sample out of a population. Thus, how do we determine when to use a chi-square test? It is when we want to test a hypothesis about a categorical variable. This is why in chi-square the null and alternative hypotheses are worded differently (there is no in the hypothesis), We test categorical variables with the following approaches (depending on what we are asking). Here are some examples (the null is stated first, the alternative below it). Example 1 The cell categories are equal The cell categories are not equal Now let’s look at some different wording based on what we are given. There are more specific. Express in terms of the key issue in the situation; however, there is flexibility here…you can
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Unformatted text preview: very likely use different words, so look at these as examples: Example 2 The outcomes are the same The outcomes are not the same Example 3 Rounds played is the same each day Rounds played is not the same each day Example 4 There is no difference in the proportions There is a difference in the proportions Example 5 The proportions are the same The proportions are not the same And so on. Here is the key to recognize chi-square: we recognize a chi-square application by seeing that we are given several categories each with observed frequencies, and are asked if the expected frequencies fit those categories. (Note: in this course we will only study the "equal expected frequencies" and not include the "unequal expected frequencies"). BTW - we also know that chi-square is typically nominal data. ...the level of measurement that relates to categories. And we must use degrees of freedom with this data (use the Chi-Square Critical Values, Appendix E)....
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