Correlation and Best-Fit Line

From the book, Chapters 15 to 17. Mina’s twelve days (loaded): r = 0.93, r² = 86%, about 2.9 more iced drinks per degree. Always look at the scatter plot: one odd point, a curve or a cut-short range can make r misleading. A strong correlation is not proof that one thing causes the other. If your rows are in time order, the correlation of their year-to-year changes shows whether a shared trend is doing all the work.