Method. Export values are aggregated to the chosen level. Flows below the minimum flow are set to zero. Locations and products below the export minimums are then dropped, RCA is computed (Balassa, relative to the retained Indonesian total), and Mcp = 1 where RCA ≥ threshold. Locations below the minimum diversity and products below the minimum ubiquity are removed. RCA is recomputed and the filters reapplied until nothing changes. Only the largest connected component of the location–product network is kept. ECI is the eigenvector for the second-largest eigenvalue of M̃cc′ = Σp Mcp Mc′p /(kc kp ), standardized, with its sign set so that it correlates positively with diversity. PCI uses the matching product-side eigenvector.
International-PCI methods. Instead of the eigenvector, a location's ECI is the average of the international PCIs (OEC, HS6, for the selected year) of the products it exports. HS6 PCIs are averaged without weights to HS4. "Average PCI" takes a simple mean over products with RCA ≥ threshold, i.e. ECIc = Σp Mcp PCIp /kc . "Export-weighted" weights every retained product by its share of the location's exports. The same filters apply, and products without an international PCI are skipped (mostly new HS2022 codes, <0.5% of value). These values stay on the international PCI scale, so 0 is the world product average.
Caveats. Ports record where goods leave the country, not where they were produced, so hub ports (Tanjung Priok, Tanjung Perak) collect goods from their hinterlands. ECI is relative to the other locations in Indonesia that are included. With only 7 island groups, the island-level ranking is coarse. Ports were assigned to provinces by hand. "Bonthan Bay, Sulawesi" is assigned to Kalimantan Timur (Bontang), because it exports LNG, ammonia and fertilizer. "Tanjung Leneng" and "Futong Terminal" are assigned on a best-guess basis (Kepulauan Riau and Riau). Kepulauan Riau and Bangka Belitung are grouped with Sumatra. Port locations on the map are approximate.
Sources. Trade by port of exit and HS4 product (2025) and product complexity: OEC . Country outlines: Natural Earth 1:50m via world-atlas. Province boundaries: indonesia-geojson-topojson-maps-with-38-provinces (CC BY 4.0), simplified. Map drawn with d3 .