Table 1.
Details about variables, measurements, and source of data
| Variables | Measurements | Source = World Bank Group URL |
|---|---|---|
| GDP | In constant US dollars (US$) | https://data.worldbank.org/indicator/NY.GDP.MKTP.KD |
| AIR | In a million-ton-kilometers | https://data.worldbank.org/indicator/IS.AIR.GOOD.MT.K1 |
| Maritime (SEA) | In TEU | https://data.worldbank.org/indicator/IS.SHP.GOOD.TU |

Figure 1.
The growth rate of air and maritime cargo volume and GDP (Original Data Series).
Table 3.
The results of ADF tests and PP tests for air transport and GDP
| ADF test | World | USA | China | Japan | India | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| p-value | Lag | p-value | Lag | p-value | Lag | p-value | Lag | p-value | Lag | |
| GDP | 0.943 | 3 | 0.356 | 3 | 0.981 | 3 | 0.946 | 3 | 0.99 | 3 |
| GDP Diff1* | 0.015 | 3 | 0.055 | 3 | 0.631 | 3 | 0.045 | 3 | 0.052 | 3 |
| AIR | 0.353 | 3 | 0.637 | 3 | 0.725 | 3 | 0.769 | 3 | 0.717 | 3 |
| AIR Diff1 | 0.021 | 3 | 0.354 | 3 | 0.058 | 3 | 0.01 | 3 | 0.364 | 3 |
| PP test | World | USA | China | Japan | India | |||||
| GDP | 0.976 | 3 | 0.485 | 3 | 0.99 | 3 | 0.987 | 3 | 0.99 | 3 |
| GDP Diff1 | 0.01 | 3 | 0.01 | 3 | 0.01 | 3 | 0.01 | 3 | 0.01 | 3 |
| AIR | 0.250 | 3 | 0.633 | 3 | 0.849 | 3 | 0.340 | 3 | 0.492 | 3 |
| AIR Diff1 | 0.01 | 3 | 0.01 | 3 | 0.01 | 3 | 0.01 | 3 | 0.01 | 3 |
Table 4.
The results of ADF tests and PP tests for maritime transport and GDP
| ADF test | World | USA | China | Japan | India | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| p-value | Lag | p-value | Lag | p-value | Lag | p-value | Lag | p-value | Lag | |
| GDP | 0.362 | 2 | 0.494 | 2 | 0.022 | 2 | 0.323 | 2 | 0.620 | 2 |
| GDP Diff1 | 0.146 | 2 | 0.426 | 2 | 0.720 | 2 | 0.426 | 2 | 0.734 | 2 |
| Maritime | 0.850 | 2 | 0.735 | 2 | 0.444 | 2 | 0.541 | 2 | 0.99 | 2 |
| Ma. Diff1 | 0.020 | 2 | 0.574 | 2 | 0.077 | 2 | 0.032 | 2 | 0.429 | 2 |
| PP test | World | USA | China | Japan | India | |||||
| GDP | 0.075 | 2 | 0.388 | 2 | 0.924 | 2 | 0.41 | 2 | 0.655 | 2 |
| GDP Diff1 | 0.01 | 2 | 0.01 | 2 | 0.01 | 2 | 0.013 | 2 | 0.014 | 2 |
| Maritime | 0.466 | 2 | 0.592 | 2 | 0.332 | 2 | 0.553 | 2 | 0.897 | 2 |
| Ma. Diff1* | 0.033 | 2 | 0.027 | 2 | 0.01 | 2 | 0.014 | 2 | 0.082 | 2 |

Figure 2.
The scatter plot of air transport and GDP for Japan.
Note: The black dot shows outliers.
Table 5.
The correlation coefficients for the first differences between air transport and GDP
| R | p-value | N | |
|---|---|---|---|
| World total | 0.679 | <0.001 | 45 |
| USA | 0.693 | <0.001 | 45 |
| China | 0.405 | <0.001 | 45 |
| Japan | –0.081 | <0.001 | 45 |
| India | 0.500 | <0.001 | 45 |
Table 6.
The correlation coefficient for the first difference between air transport and GDP.
| Country | R | p-value | N |
|---|---|---|---|
| Japan | 0.2142 | 0.1627 | 43 |
Table 7.
The correlation coefficients for the first differences of maritime transport and GDP
| R | p-value | N | |
|---|---|---|---|
| World Total | 0.746 | < 0.001 | 19 |
| USA | 0.869 | < 0.001 | 19 |
| China | 0.403 | 0.070 | 19 |
| Japan | 0.869 | < 0.001 | 19 |
Table 8.
The results of Granger causality tests for the first differences between air transport and GDP
| Area/country | AIR to GDP | GDP to AIR | ||
|---|---|---|---|---|
| F-value | p-value | F-value | p-value | |
| World total | 0.08 | 0.778 | 4.841 | 0.030 |
| USA | 3.776 | 0.055 | 5.112 | 0.026 |
| China | 0.733 | 0.572 | 1.661 | 0.169 |
| Japan | 8.693 | 0.004 | 0.566 | 0.454 |
| India | 9.396 | 4.17E–06 | 3.634 | 0.009 |




