Go to the library or the Internet and, for a particular year, put together a data set of profits in agriculture in different geographical units of your state or country (e.g., counties of a U.S. state; states of a federal government). Locate data on the average annual temperature at a typical location in each geographic unit. For each geographic unit you should have two numbers: agricultural profits and average annual temperature. Plot these data (profits on one axis, temperature on the other). Is there a relationship? Are there additional variables that might increase the explanatory power of your data? What can you conclude about the overall effect on profits of a \(3^{\circ} \mathrm{C}\) increase in the annual temperature in each of the geographic units?