Dani Rodrik on TPP Economic Estimates

This is from economist, and trade skeptic (to some extent), Dani Rodrik:

The bottom line is that neither side’s models generate numbers reliable enough on which a case for or against the TPP can be made.

I'm a lot more pro-trade than Dani Rodrik is, but I tend to agree with him about the reliability of the numbers. That's the case generally, but it's particularly true where "non-tariff barriers" are at issue:

The Petri-Plummer study predicts that the bulk of the economic benefits of the TPP will come from reductions in non-tariff barriers (such as regulatory barriers on imported services) and lower obstacles to foreign investment. But the modeling of these effects is an order of magnitude more difficult than in the case of tariff reductions. The assumptions needed to do so are not standard and require many arbitrary short cuts.