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Chi-square test or c2 test

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Chi-square test or c2 test

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    1. Chi-square test or c2 test

    3. Chi-square test Used to test the counts of categorical data Three types Goodness of fit (univariate) Independence (bivariate) Homogeneity (univariate with two samples)

    4. c2 distribution

    5. c2 distribution Different df have different curves Skewed right As df increases, curve shifts toward right & becomes more like a normal curve

    6. c2 assumptions SRS reasonably random sample Have counts of categorical data & we expect each category to happen at least once Sample size to insure that the sample size is large enough we should expect at least five in each category. ***Be sure to list expected counts!!

    7. c2 formula

    8. c2 Goodness of fit test Uses univariate data Want to see how well the observed counts fit what we expect the counts to be Use c2cdf function on the calculator to find p-values

    9. Hypotheses written in words H0: the observed counts equal the expected counts Ha: the observed counts are not equal to the expected counts Be sure to write in context!

    16. c2 test for independence Used with categorical, bivariate data from ONE sample Used to see if the two categorical variables are associated (dependent) or not associated (independent)

    17. Assumptions & formula remain the same!

    18. Hypotheses written in words H0: two variables are independent Ha: two variables are dependent Be sure to write in context!

    20. If beef preference is independent of geographic region, how would we expect this table to be filled in?

    21. Expected Counts Assuming H0 is true,

    22. Degrees of freedom

    25. c2 test for homogeneity Used with a single categorical variable from two (or more) independent samples Used to see if the two populations are the same (homogeneous)

    27. Hypotheses written in words H0: the two (or more) distributions are the same Ha: the distributions are different Be sure to write in context!

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