Beide haben vor allem auf dem Gebiet der Makroökonomie geforscht. Insbesondere haben sie an der Entwicklung von empirischen Analysemethoden gearbeitet. Dabei ging es ihnen darum, zu erforschen, wie man Erwartungen modellieren und damit Ursache und Wirkung identifizieren kann.
Zur Begündung sagte das Komitee:
"Thomas Sargent has shown how structural macroeconometrics can be used to analyze permanent changes in economic policy. This method can be applied to study macroeconomic relationships when households and firms adjust their expectations concurrently with economic developments. Sargent has examined, for instance, the post-World War II era, when many countries initially tended to implement a high-inflation policy, but eventually introduced systematic changes in economic policy and reverted to a lower inflation rate."
"Christopher Sims has developed a method based on so-called vector autoregression to analyze how the economy is affected by temporary changes in economic policy and other factors. Sims and other researchers have applied this method to examine, for instance, the effects of an increase in the interest rate set by a central bank. It usually takes one or two years for the inflation rate to decrease, whereas economic growth declines gradually already in the short run and does not revert to its normal development until after a couple of years."
Ein Nobelpreis, den man guten Gewissens für die Ökonometrie zählen kann.