chapter5 - Twowaytables PSLS chapter 5 2009 W. H. Freeman...

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    Two-way tables PSLS chapter 5 © 2009 W. H. Freeman and Company
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Objectives (PSLS chapter 5) Two-way tables Two-way tables Marginal distributions Relationships between categorical variables Conditional distributions Simpson’s paradox
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400 1380 416 1823 188 1168 A study has a two-way, or block, design if two categorical factors are studied with several levels of each factor. Two-way tables organize data about two categorical variables with any number of levels/treatments obtained from a two-way design. ( There are now two ways to group the data. ) Two-way tables    First factor: Parent smoking status Second factor: Student smoking status High school students were asked whether they smoke, and whether their parents smoke:
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Marginal distributions We can look at each categorical variable in a two-way table separately by studying the row totals and the column totals. They represent the marginal distributions, expressed in counts or percentages. (They are written as if in a margin.) 400 1380 416 1823 188 1168 Marginal distribution for parental smoking Marginal distribution for student smoking
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1380 33.1% 416 1823 41.7% 188
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This note was uploaded on 10/07/2011 for the course BSTT 400 taught by Professor Sallyfreels during the Fall '11 term at Ill. Chicago.

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chapter5 - Twowaytables PSLS chapter 5 2009 W. H. Freeman...

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