Converging Aggregates, Diverging Components: Iran's 2021 Benchmark Revision

Productivity Research Notes (PRN Series), No. 2617 Iran maintains two independent national accounts systems—SCI and CBI—whose GDP estimates differed by 38% under the previous benchmarks. The 2021 benchmark revision narrowed the gap to 20%, but this aggregate convergence is misleading. On the expenditure side, consumption and gross fixed capital formation reversed which series was larger, so the narrowing largely reflects offsetting movements rather than genuine agreement. On the production side, electricity remains a major outlier, with SCI’s estimate still 7.6 times that of CBI, plausibly reflecting different price-valuation bases. Inventory changes may also function as balancing items rather than measures of genuine stockbuilding. The note shows that aggregate convergence alone is not informative about measurement reliability; component-level diagnosis is required.