| Level | First Difference | ||||
Variable | ADF | PP | ADF | PP | ||
Crude oil | −1.874 | −1.503 | 8.124** | −7.978** | ||
Gasoline | −2.558 | −2.596 | 10.692** | 10.684** | ||
Gas oil | −2.713 | −3.079 | 14.992** | 15.745** | ||
RFO | −1.490 | −1.144 | −6.996** | −6.960** | ||
Premix | −2.778 | −2.177 | −5.912** | −8.687** | ||
Exchange rate | −0.058 | −0.304 | −7.393** | −7.311** | ||
Inflation rate | 0.808 | 0.828 | −8.258** | −8.258** | ||