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Understanding and Applying Basic Statistical Methods Using R by Rand R. Wilcox

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Chapter 8CORRELATION AND REGRESSION

A common goal is determining whether two variables are dependent and, if they are dependent, trying to understand the nature of the association. Is there an association between breast cancer rates and exposure to solar radiation? If yes, how might it be described in an effective manner? What is the association between weight gain in infants and the amount of ozone in the air? How strong is the association? This chapter describes some of the more basic techniques aimed at answering these questions.

8.1 Regression Basics

A fundamental issue in a regression analysis can be described in general terms as follows. Consider any two variables, say c08-math-0001 (e.g., marital aggression in the home) and c08-math-0002 (e.g., cognitive functioning of children living in the home). How might we estimate the typical value of c08-math-0003 if we are told the value of c08-math-0004? If marital aggression in the home is relatively low, is the typical level of cognitive functioning of children living in the home higher compared to homes where marital aggression is relatively high? The most common strategy for answering ...

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