D.30 Answers: Relationships between two quantitative variables

Answers to exercises in Sect. 33.6.

Answer to Exercise 33.1: Linear, positive, very little variation (i.e., strong relationship). Of note: The observation in the bottom left is very different from the rest of the data, but still maintains the linear relationship.
Answer to Exercise 33.2: Non-linear; higher wind speed related to higher DC output (in general); a small to moderate amount of variation. The DC output increases as wind speed increases, but not linearly.
Answer to Exercise 33.3: The relationship probably linear… but a few observations at the top right look a bit different. Variation seems to increase a little as the Age increases. Of note:: A few observations in the top right of the scatterplot seem to not follow the linear relationship.
Answer to Exercise 33.4: Approximately linear; positive relationship; variation seems to get larger for a larger number of cases.