Applied causal inference, blended-finance research, and teaching.https://ihelfrich.github.io/https://ihelfrich.github.io/writing/hello-from-the-hub/https://ihelfrich.github.io/writing/hello-from-the-hub/Notes from the rebuild. Why I picked Astro + Pagefind over Docusaurus, what the hub is for, and what comes next.Mon, 11 May 2026 00:00:00 GMTwritingmetatoolinghttps://ihelfrich.github.io/research/gonchar-helfrich-2026-effective-distance-panel/https://ihelfrich.github.io/research/gonchar-helfrich-2026-effective-distance-panel/Builds the first global, time-varying, satellite-calibrated, multi-modal bilateral effective-distance panel for 200 countries over 2000-2024. The construction uses VIIRS and DMSP-VIIRS nightlights, WorldPop / GHS-POP / HRSL gridded population, and OpenStreetMap-derived transport networks (road, maritime, air) to compute least-cost-path distances with endogenous mode choice. Validated in the Yotov et al. (2016) structural gravity framework with Weidner-Zylkin (2021) bias correction. Three live counterfactuals: the 2021 Suez closure (Ever Given), the 2023 Panama Canal drought, and the 2024 Houthi Red Sea rerouting. Material revisions to ACR welfare numbers under each. Released as CC-BY public-good infrastructure.Thu, 01 Jan 2026 00:00:00 GMTresearchtradegravityeffective-distancesatellite-economicspanel-datahttps://ihelfrich.github.io/research/gonchar-helfrich-2026-ukraine/https://ihelfrich.github.io/research/gonchar-helfrich-2026-ukraine/Applies the Penumbra closed-loop observation framework to the best-instrumented wartime economic reorganization in history. Combines pre-war hromada-level administrative granularity, dense commercial satellite coverage (Planet, Maxar, Sentinel, VIIRS Black Marble), AIS data on Black Sea grain corridors, displaced-population tracking from UN/IOM and Ukrainian state registers, and KSE Institute damage and trade-disruption data. Decomposes the spatial reorganization of Ukrainian economic activity between Q1 2022 and Q1 2026 into destruction, evacuation/relocation, conscription-driven labor withdrawal, and sectoral adaptation (IT services, agriculture, defense-industrial expansion). Produces a quarterly Ukraine Shadow-Activity Index as a public-good output.Thu, 01 Jan 2026 00:00:00 GMTresearchukrainewartime-economyspatial-laborsatellite-economicssanctionshttps://ihelfrich.github.io/research/helfrich-2026-aroe/https://ihelfrich.github.io/research/helfrich-2026-aroe/A fixed-point problem on the 2-Wasserstein space over a compact domain. Given a base transport cost, a smooth congestion-response function, a stochastic observation operator, and a feedback weight, the paper seeks measures that are optimal-transport plans for a measure-dependent cost. The cost-as-functional-of-equilibrium structure places the problem outside the standard optimal-transport machinery used in economics (where the cost is fixed). Existence is established under three regularity hypotheses; a fourth feedback-contractivity hypothesis delivers uniqueness with a quantitative half-order Wasserstein stability estimate. The economic motivation is quantitative spatial equilibrium with endogenous observation: settings where a remote-sensing observation operator enters the equilibrium trade cost. The result sits inside the Allen et al. (2024) umbrella uniqueness theorem and adds a measure-dependent cost channel and a pre-period conditional-moment restriction.Thu, 01 Jan 2026 00:00:00 GMTresearchoptimal-transportfixed-pointspatial-equilibriumsatellite-economicshttps://ihelfrich.github.io/research/helfrich-2026-nmtc-rural-gap/https://ihelfrich.github.io/research/helfrich-2026-nmtc-rural-gap/Decomposes the rural-versus-urban leverage gap in the U.S. New Markets Tax Credit using CDE (Community Development Entity) fixed effects. The raw gap of −0.262*** in private-leverage ratio collapses to −0.047 (p = 0.64, insignificant) once between-CDE selection is absorbed. Approximately 80% of the aggregate rural penalty is between-CDE allocation, not within-CDE deployment. The rural mobilization debate is therefore an intermediary-selection problem, not a market-structure problem, with direct implications for CDFI Fund allocation rules.Thu, 01 Jan 2026 00:00:00 GMTresearchnmtcblended-financeruralintermediary-FEhttps://ihelfrich.github.io/research/helfrich-2026-penumbra/https://ihelfrich.github.io/research/helfrich-2026-penumbra/The umbrella theory paper for the Penumbra program. Official trade and production statistics rest on a counterparty-declaration assumption that is increasingly violated by sanctioned-corridor activity (Russian seaborne crude under the 2022 oil cap, Iranian oil since 2018, Sahelian gold smuggled to the UAE, gray-market rare earths). The paper formalizes the measurement gap as a closed-loop problem on Wasserstein space: an equilibrium measure whose cost depends on its own remote-sensing image. Existence under standard assumptions; quantitative uniqueness under a feedback-contractivity hypothesis. The framework is the basis for Paper 1 (theory of adaptive-regularization observation equilibria) and Paper 2 (empirical Russian-crude application).Thu, 01 Jan 2026 00:00:00 GMTresearchsanctionssatellite-economicsoptimal-transportmeasurementshadow-tradehttps://ihelfrich.github.io/research/helfrich-2026-russian-crude/https://ihelfrich.github.io/research/helfrich-2026-russian-crude/Empirical companion to the AROE theory paper. Tests the contraction hypothesis (H4) in the corridor where the closed-loop observation problem is sharpest: Russian seaborne crude under the 2022-present sanctions regime. Uses AIS-track data, port-arrival records, and shadow-fleet flag transitions to back out the observation operator's Frechet derivative. Provides the first direct empirical estimate of the feedback-contractivity constant in a real-world quantitative spatial setting.Thu, 01 Jan 2026 00:00:00 GMTresearchsanctionsrussian-crudeAISsatellite-economicsempirical-OThttps://ihelfrich.github.io/writing/welcome-to-plot-and-policy/https://ihelfrich.github.io/writing/welcome-to-plot-and-policy/Migrated from the old WordPress site. A short note on why I started a public lab notebook in March 2025, what was supposed to live there, and how the project drifted into the broader hub you're reading now.Fri, 07 Mar 2025 00:00:00 GMTwritingmetaarchivehttps://ihelfrich.github.io/research/gonchar-helfrich-2025-spotlight/https://ihelfrich.github.io/research/gonchar-helfrich-2025-spotlight/The distribution of population across and within countries naturally relates to the distribution of economic production. We explore differences in gravity-model estimates of trade that take spatial factors of population distribution seriously, introducing a novel geodesic distance measure between countries using population-weighted centroids as endpoints for bilateral distance. Canonical gravity models have relied on time-invariant CEPII distance measures since 2004; we show that incorporating annual VIIRS nightlight intensity and gridded population yields measurably better gravity fit. The OVDL (Origin-VIIRS to Destination-LandScan) measure is the headline construction. April 2025 preprint; the full panel and structural-gravity validation are in Paper 5 (Effective Distance, in preparation).Wed, 01 Jan 2025 00:00:00 GMTresearchtradegravitynightlightseffective-distancegeospatialhttps://ihelfrich.github.io/research/helfrich-2024-ssrn-4772016/https://ihelfrich.github.io/research/helfrich-2024-ssrn-4772016/Introduces a framework that unifies economic equilibrium and optimal transport on infinite-dimensional Hilbert spaces, building on tensor-valued measures and nonlinear operator theory. Establishes existence and uniqueness of equilibrium under mild assumptions on preferences and endowments, characterizes equilibrium allocations as optimal transport plans, and represents equilibrium prices as gradients of convex potential functions. The paper is the analytical foundation for the closed-loop observation work in Papers 0 and 1.Mon, 01 Jan 2024 00:00:00 GMTresearchoptimal-transportequilibrium-theoryinfinite-dimensionalHilbert-spaces