| Abstract: | In this article it is argued that, if two products or geographicareas belong in the same market, their relative price must bestationary. Hence stationarity tests like the Augmented Dickey-Fullerand the KPSS can be helpful in delineating the relevant marketfor antitrust purposes, particularly for abuses of dominantpositions and agreements between competitors. The proposed procedureis strictly related to cointegration analysis but is simplerand has more general validity. An application to the Italianmilk market illustrates the technique. |
