Weighted Harmonized System & Standard International Trade Classification Conversion Tables

This dataset provides conversion weights for translating product codes between different trade classification systems. Each record contains a source classification product code, target classification product code, and a conversion weight for the product pair. Purpose and Context Countries adopt new trade classification systems at different times, and product codes are regularly revised, split, or merged over time. Simple one-to-one mappings between classification vintages often result in loss of detailed product information and create discontinuities in time series data. To address this challenge, we have developed data-driven conversion weights that enable accurate translation of trade values between classification systems while preserving product detail. Methodology These conversion weights are generated using empirical trade data to determine how products in one classification system map to products in another system. When combined with reliability-weighted mirror data, this approach produces bilateral, product-level trade datasets that are consistent across countries and time periods. This methodology improves data coverage, reduces reporting discrepancies, and supports robust long-run analysis of global trade patterns. Related Resources The data and methodology are described in detail in our peer-reviewed publication: Bustos et al. (2026), Tackling Discrepancies in Trade Data: The Harvard Growth Lab International Trade Datasets, Scientific Data. For a visual explanation of the Growth Lab's trade data methodology, please visit our companion website. These conversion weights form a critical component of the data infrastructure underlying the Atlas of Economic Complexity.