[論文レビュー] Uncovering Functional Blocks in Interregional Production Networks: Evidence from Input-Output Linkages in Japan

Shota Fujishima|arXiv (Cornell University)|Mar 26, 2026

Regional Economics and Spatial Analysis被引用数 0

ひとこと要約

tldr: The paper filters gravity-driven effects from Japan’s interregional production network and uses a weighted stochastic blockmodel on the residuals to reveal latent functional blocks with strong regional coherence and cross-regional integration.

ABSTRACT

This paper examines the latent functional block structure of Japan's production network using interregional input-output data. To isolate non-trivial production linkages, we first estimate a structural gravity model to account for spatial frictions and economic scale, and then apply a weighted stochastic blockmodel (SBM) to the resulting residual network. Because these residual linkages often connect distant regions, the SBM is well suited to grouping region-industry pairs based on their shared macroeconomic roles. The results reveal that even after explicitly filtering out the mechanical effects of geographic proximity, the network is organized into functional blocks that maintain a high degree of regional coherence. Beyond this baseline spatial clustering, we find evidence of cross-regional integration, a structural bifurcation between manufacturing and urban services in metropolitan areas, and broadly spanning primary sectors. These findings provide a network-based perspective on regional coordination, offering guidance for how structurally defined production blocks-rather than simple geographic proximity-can inform wide-area policy design.

研究の動機と目的

• Identify the latent functional block structure of Japan's interregional production network.
• Isolate non-gravity (non-proximity) linkages by estimating a structural gravity model and constructing a residual network.
• Detect function-based regional blocks using a weighted stochastic blockmodel.
• Assess regional coherence, cross-regional integration, and metropolitan bifurcations in the residual network.
• Discuss implications for wide-area regional coordination and policy design.

提案手法

• Estimate a gravity model with Poisson pseudo-maximum likelihood (PPML) on interregional input–output data to filter distance and size effects.
• Construct a residual network from log-deviations of observed versus predicted flows, retaining positive residuals as the backbone.
• Apply a degree-corrected weighted stochastic blockmodel (SBM) with exponential edge weights to the residual network.
• Infer the optimal block structure by minimizing description length in Peixoto’s nonparametric Bayesian framework.
• Interpret blocks as region–industry functional blocks reflecting macroeconomic roles rather than mere proximity.

実験結果

リサーチクエスチョン

• RQ1 Do region–industry pairs organize into functional blocks beyond geographic proximity after gravity filtering?
• RQ2 What is the extent of regional coherence in the residual linkage structure?
• RQ3 Are there cross-regional integrations and metropolitan bifurcations in the functional blocks?
• RQ4 How can identified functional blocks inform wide-area regional coordination and policy design?

主な発見

• The residual network after gravity filtering exhibits a high degree of regional coherence.
• Chugoku and Shikoku regions show structural equivalence, acting as a cohesive macroeconomic zone.
• Metropolitan areas like Kanto and Kinki display a bifurcation between broad manufacturing bases and urban services.
• Mining roles and certain primary/infrastructure sectors span broadly across Eastern Japan, indicating cross-regional linkages.
• Okinawa’s industries collapse into a single region-wide cluster, highlighting unique institutional frictions.
• Overall, functional blocks reveal latent interdependencies that transcend geographic proximity and inform regional coordination.