Gravity Model of Trade Calculator

Formula first

Overview

The Gravity Model of Trade is a fundamental tool in international economics, positing that trade between two countries is directly proportional to their economic sizes (e.g., GDPs) and inversely proportional to the distance between them. Analogous to Newton's law of universal gravitation, this model helps explain observed trade patterns, predicting that larger, closer economies will trade more. It provides a robust framework for analyzing the determinants of international trade and assessing the impact of trade policies or agreements.

Symbols

Variables

$Y_i$ = GDP of Country i, $Y_j$ = GDP of Country j, $D_{ij}$ = Distance between i and j, A = Trade Constant, $T_{ij}$ = Trade Flow

Apply it well

When To Use

When to use: Use this equation to estimate the volume of trade between two countries or regions, to analyze the impact of factors like economic size and geographical distance on trade, or to identify 'anomalous' trade flows that might suggest the presence of trade barriers or special agreements. It's particularly useful for policy analysis in international trade.

Why it matters: The Gravity Model is crucial for understanding global trade dynamics, informing trade policy, and evaluating the effects of economic integration or fragmentation. It helps economists and policymakers predict future trade trends, identify potential trade partners, and design effective strategies for economic development and international cooperation.

Avoid these traps

Common Mistakes

• Ignoring the constant 'A' or misinterpreting its role as a catch-all for non-distance/size factors.
• Using inappropriate measures for distance (e.g., straight-line distance when trade routes are complex).
• Not accounting for multilateral resistance terms in more advanced applications.

One free problem

Practice Problem

Consider two countries, Alpha and Beta. Country Alpha has a GDP ($Y_i$) of $20$ trillion USD, and Country Beta has a GDP ($Y_j$) of $15$ trillion USD. The distance ($D_{ij}$) between them is $5000$ km. If the trade constant ($A$) is $0.000000000001$ (or $1\times 10^{-12}$), calculate the predicted trade flow ($T_{ij}$) between Alpha and Beta.

Solve for: Tij

Hint: Remember to use scientific notation for large numbers and ensure all units are consistent.

The full worked solution stays in the interactive walkthrough.

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Related Formulas

References

Sources

1. International Economics: Theory and Policy by Paul R. Krugman, Maurice Obstfeld, and Marc Melitz
2. Wikipedia: Gravity model of trade
3. World Trade Flows: An Analysis of Production and Trade Patterns and Policies by Jan Tinbergen
4. Krugman, Paul R., Obstfeld, Maurice, & Melitz, Marc J. (2018). International Economics: Theory & Policy.
5. Krugman, Paul R., Maurice Obstfeld, and Marc J. Melitz. International Economics: Theory & Policy. Pearson Education.
6. Anderson, James E., and Eric van Wincoop. 'Gravity with Gravitas: A Solution to the Border Puzzle.' American Economic Review 93, no.
7. Tinbergen, J. (1962). Shaping the World Economy. New York: Twentieth Century Fund. (Econometric formulation)