The rather well known "environmental Kuznets curve" in environmental economics shows a relationship between pollution and income per capita that follows an inverted U-shape. Do some wishful thinking: What data would you like to have to test this relationship? Specify a simple linear relationship that has a chance of testing this prediction given a sample from the population Intuitively explain the variation in the data that you exploit to identify the coefficients What assumption(s) do you need to establish causality? Intuitively what does this mean/say? Can you think of any information that's still in the error term? Given your answer to the previous subquestion, do you expect that the assumption E(u|income)=0 holds