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Table 1 Stationarity tests

From: Antitrust intervention and price transmission in pasta supply chain

  Jan 2005-Aug 2008 Sept 2008-Sept 2013
  ADF KPSS ADF KPSS
Pasta price −2.088 0.485b −1.597 0.515b
Rising semolina price
Current 0.162 0.964a 1.096 1.068a
One month 0.176 0.939a 2.652 2.029a
Two month 0.193 0.911a 2.680 2.035a
Three month 0.237 0.883a 2.690 2.038a
Falling semolina price
Current 0.665 1.041a 0.947 0.647a
One month 0.254 0.698b 1.191 0.641b
Two month 0.741 0.821a 0.976 0.635b
Three month 0.743 0.938a 1.050 1.141a
Other costs
Labour 2.901 0.948a 1.111 1.718a
Energy 1.711 0.908a −0.515 0.463b
  1. In ADF test, hypothesis null is unit root while in KPSS is stationarity
  2. aStatistically different from zero at 1 %; bStatistically different from zero at 5 %
  3. In ADF test, hypothesis null is unit root while in KPSS is stationarity