Today the Royal Swedish Academy of Sciences awarded two Americans, Thomas Sargent and Christopher Sims, the Nobel in economics. The prize's justification is as follows: "for their empirical research on cause and effect in the macroeconomy".
According to the prize committee the winners developed methods for answering questions such as how economic growth and inflation are affected by a temporary increase in the interest rate or a tax cut. Sargent and Sims, both 68 years old, carried out their research independently in the 1970s and 1980s.More details on the prize can be found here.
For the winners' personal webpages: Thomas Sargent and Chris Sims.