“lobbying effect”. As argued, time costs of trade matters more for the exports of time-sensitive industries. Producers of these sectors may provide a strong political pressure for trade facilitation. The lobbying effects may also be self-reinforcing. Export growth of time-sensitive industries will increase their incentive to lobby and strengthen their bargaining power. However, not all firms will engage in political bargaining. We would like to argue that larger or foreign owned companies are more likely to put pressures on governments as they have more resources and are more visible. One way of assessing how serious the bias could be is to restrict the sample to domestic SMEs (Columns 1, 2, 7 and 8 of Table 6). Members of business associates are another group of firms that may influence trade related policies. For 60 surveys, we have information on whether a firm belongs to a business association and whether the organization provides lobbying services. As a second check on the reverse causality problem, we exclude members of any business association involving in lobbying (Columns 3, 4, 9 and 10 of Table 6). The estimated coefficients on time interaction remain close to baseline. We are more confident that our results are not entirely driven by reverse causality.

Major exporters, especially those of time-sensitive industries, have more incentive to push for trade facilitation reforms as well. Including them in our estimation is another channel that the lobbying effects may bias our results upward. To assess this potential bias, we restrict the sample to a subset of firms with export intensities less than 50 percent (Columns 5, 6, 11 and 12 of Table 6). The estimates on time interaction stays significantly negative for both models. But, the magnitude of the estimates is reduced and the significant levels also drop when controlling for other industry interactions. Overall, the suspected lobbying effects may explain parts of the relationship, but not enough to change the whole story.

# **Extensions**

The results presented to this point have not considered the possibility that the relationship between time interaction and export performance may vary over country groups. Various country factors may affect the relationship, including levels of economic development, institutional quality, etc. We augment equations (4) and (5) by adding a triple interaction between time sensitivity, export time and income levels which we use to capture the overall economic and social development of a country (Column 1, 2, 5 and 6 of Table 7). The coefficients on time interaction remain close to the baseline results. The estimated coefficients on the triple interaction for both equations appear to be positive and significant at first. But, they are small and lose statistical significance when controlling for all other interactions. It indicates that the relationship between export time and the differences in export performance across industries applies to developing economies with different income levels but may be slightly stronger in lower income countries.

Productivity is a key driver behind the export performance of a company. As a next extension, we want to check whether the impact of export time differs across productivity levels. We argument the specification with a triple interaction between time sensitivity, export time, and value-added per labor (Column 3, 4, 7 and 8 of Table 7). The coefficients on time interaction are consistent with baseline. No significant results have been found for the new triple-interaction term. The impact of time as a determinant of comparative advantage is not affected by productivity levels.

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