When drug pushers become leading indicators of economic conditions.
The US Justice Department (DoJ) and the Drug Enforcement Agency’s (DEA) latest report on the trends of methamphetamine prices and purity on the samples they buy from dealers shows some strong correlation. In the last 20 years, methamphetamine prices (US$/gram) have shown a 91% R-squared correlation (i.e. very high) to purity. See link above for fuller details.