Whew, we've been through a lot in this chapter, and I commend you for sticking it out. Your tenacity will be well rewarded when you start using regression analysis in your own projects or to research like a professional.
We started off with the basics: how to describe a line, simple linear relationships, and how a best-fit regression line is determined. You saw how we can use R to easily plot these best-fit lines.
We went on to explore regression analysis with more than one predictor. You learned how to interpret the loquacious lm summary output, and what everything meant. In the context of multiple regression, you learned how the coefficients are properly interpreted as the effect of a predictor controlling for all other predictors. You're now aware that controlling for and thinking about confounds is one of the cornerstones of statistical thinking.
We discovered that we weren't limited to using continuous predictors, and that, using dummy coding, we can not only model the effects...