Cost of Living 2020, revisited. For the first model considered in Exercise 27, with all four predictors in the model, a plot of Leverage values shows the two largest values are San Francisco, United States (0.1166) and Seoul, South Korea (0.1017).

a) By examining the values of their predictor variables, find out why these two cities might be such high leverage points.

b) Why does Seoul still show up as an inf luential point in the diagnostics of the 2 predictors model?