6. This problem illustrates spurious correlation. Obtain monthly data on US Consumer Price Index (or Canadian from Statistics Canada or another country-it's not particularly important which series you use as long as it's monthly and the level, not rate of change of CPI; in other words you 2 want the price level, not inflation rate) from, the web site of the Federal Reserve Bank of St. Louis: http://research. stlouisfed.org/. There are various CPI series available, but you might use CPI for all urban con- sumers, all items, US city average, series label CPIAUCSL. Call this series P. Next, obtain monthly global CO2 levels measured at the Mauna Loa observatory, from the global monitoring laboratory of the NOAA: https://gml . noaa. gov/ccgg/trends/data.html. (Click on '(CSV)' to download.) Call this series C