Table 4 Results of ADF test for stationarity 2000 to 2021 data
From: Effects of crude oil prices on copper and maize prices
| Â | With constant | With constant and trend | Without constant and trend |
|---|---|---|---|
t-statistic (p value) | t-statistic (p value) | t-statistic (p value) | |
LOG_MAIZE | − 1.572 (0.4955) | − 2.0804 (0.5538) | 0.8585 (0.8947) |
LOG_COPPER | − 1.6859 (0.4372) | − 2.0531 (0.5690) | 0.8882 (0.8995) |
LOG_CRUDE_OIL | − 2.2859 (0.1773) | − 2.3329 (0.4142) | 0.2805 (0.7665) |
d(LOG_MAIZE) | − 3.2940** (0.0162) | − 3.2537* (0.0765) | − 3.1854*** (0.0015) |
d(LOG_COPPER) | − 10.1516*** (0.0000) | − 10.1394*** (0.0000) | − 10.1017*** (0.0000) |
d(LOG_CRUDE_OIL) | − 10.623*** (0.0000) | − 10.6157*** (0.0000) | − 10.6228*** (0.0000) |
Result | I(1) | I(1) | I(1) |