CESifo Conference Centre, Munich Gravity Redux: Structural Estimation of Gravity Equations with Asymmetric Bilateral Trade Costs
Bibliographic record
Abstract
Theoretical foundations for estimating gravity equations were enhanced recently in Anderson and van Wincoop (2003). Though elegant, the model assumes sym-metric bilateral trade costs to generate an estimable set of structural equations. In reality, however, trade costs (and trade flows) are not bilaterally symmetric. We use the simple workhorse Krugman-type monopolistic-competition/increasing-returns-to-scale model of trade assuming only multilateral trade balance to allow for asymmetric bilateral trade costs. A Monte Carlo analysis of our general equilibrium model demonstrates – in the presence of asymmetric bilateral trade costs – that the bias of the Anderson-van Wincoop approach is at least an order-of-magnitude larger than that using our approach for computing general equilibrium comparative statics. We then confirm empirically the difference of our approach and that of Anderson and van Wincoop in the Canadian-U.S. case allowing asymmetric effects of national borders. Furthermore, we apply our approach empirically to the more general case
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.011 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.052 | 0.008 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".