Transparency and Forecasting: The Impact of Conditioning Assumptions on Forecast Accuracy
Katja Heinisch, Christoph Schult, Carola Stapper
Applied Economic Letters,
forthcoming
Abstract
This study investigates the impact of inaccurate assumptions on economic forecast precision. We construct a new dataset comprising an unbalanced panel of annual German GDP forecasts from various institutions, taking into account their underlying assumptions. We explicitly control for different forecast horizons to reflect the information available at the time of release. Our analysis reveals that approximately 75% of the variation in squared forecast errors can be attributed to the variation in squared errors of the initial assumptions. This finding emphasizes the importance of accurate assumptions in economic forecasting and suggests that forecasters should transparently disclose their assumptions to enhance the usefulness of their forecasts in shaping effective policy recommendations.
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Climate Policy and International Capital Reallocation
Marius Fourné, Xiang Li
Journal of Financial Stability,
Vol. 82 (February),
2026
Abstract
This study employs bilateral data on external assets to examine the impact of climate policies on the reallocation of international capital. We find that the stringency of climate policy in the destination country is significantly and positively associated with an increase in the allocation of portfolio equity and banking investment to that country. However, it does not show significant effects on the allocation of foreign direct investment and portfolio debt. Our findings are not driven by valuation effects, and we present evidence that suggests diversification, suasion, and uncertainty mitigation as possible underlying mechanisms.
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14.01.2026 • 2/2026
Compliance with the EU fiscal rules requires extensive consolidation – Medium-term projection of macroeconomic developments and public finances in Germany
Germany faces considerable structural burdens from both macroeconomic and fiscal perspectives, as potential growth is likely to be significantly lower than in past decades. A projection by the Halle Institute for Economic Research (IWH) on macroeconomic developments up to the year 2040 shows that, under unchanged fiscal policies, public debt can be expected to continue rising. The federal government's fiscal-structural plan assumes compliance with EU requirements, but this is only achievable under the assumption of high global spending cuts that have not yet been specified in detail.
Oliver Holtemöller
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Cross-border Transmission of Climate Policies Through Global Production Networks
Marius Fourné
IWH Discussion Papers,
No. 19,
2025
Abstract
Climate policies do not operate in isolation but propagate through global production networks, affecting industries beyond national borders. This paper combines international input-output data with a granular instrumental variable approach to capture how foreign regulations transmit through upstream and downstream linkages. Distinguishing between market-based policies, non-market regulations, and technology support, the analysis shows that foreign climate policies can enhance domestic productivity, with effects shaped by industry characteristics and operating through technological adjustment along supply chains. The results underscore the importance of accounting for international spillovers when evaluating the economic impact of environmental regulation.
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Wirkung der Verwendung der Mittel des Sondervermögens Infrastruktur und Klimaneutralität sowie der zusätzlichen Bundesmittel für Verteidigung, Zivil- und Bevölkerungsschutz auf das Potenzialwachstum in Mecklenburg-Vorpommern
Andrej Drygalla, Katja Heinisch, Oliver Holtemöller, Axel Lindner, Christoph Schult, Anna Solms, Götz Zeddies
IWH Policy Notes,
No. 3,
2025
Abstract
Schriftliche Anhörung des Finanzausschusses des Landtags Mecklenburg-Vorpommern
Welche Wachstumsimpulse können zusätzliche, kreditfinanzierte Finanzmittel für Infrastruktur, Klimaneutralität und Verteidigung in Mecklenburg-Vorpommern setzen? Im Rahmen einer schriftlichen Anhörung des Finanzausschusses des Landtages Mecklenburg-Vorpommern beantwortet das IWH Fragen zur Verwendung der Finanzmittel und zur möglichen Wirkung von zusätzlichen Investitionen auf das Produktionspotenzial und das Wirtschaftswachstum in Mecklenburg-Vorpommern. Angesichts der demographischen Entwicklung ist die Arbeitsproduktivität der Schlüssel zur Verbesserung der Wachstumsaussichten des Landes.
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Zwölf-Punkte-Kompass zur Überwindung der deutschen Wachstumsschwäche
Geraldine Dany-Knedlik, Oliver Holtemöller, Stefan Kooths, Torsten Schmidt, Timo Wollmershäuser
Wirtschaftsdienst,
forthcoming
Abstract
Die Projektgruppe Gemeinschaftsdiagnose prognostiziert für das Jahr 2025 einen leichten Zuwachs des Bruttoinlandsprodukts in Deutschland um 0,2 %. Im weiteren Prognosezeitraum stimuliert die expansive Finanzpolitik die Konjunktur. Die Institute prognostizieren für die kommenden beiden Jahre Expansionsraten von 1,3 % und 1,4 %. Strukturelle Probleme wie abnehmende Wettbewerbsfähigkeit und der demografische Wandel bleiben bestehen. Um Wachstumsperspektiven für die deutsche Wirtschaft zu schaffen, bedarf es einer umfangreichen Reformpolitik. Zur Orientierung präsentieren die Institute einen Zwölf-Punkte-Kompass für den Herbst der Reformen.
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Employment Effects of Investment Grants and Firm Heterogeneity
Eva Dettmann, Antje Weyh, Mirko Titze
Regional Studies,
Vol. 59 (1),
2025
Abstract
This study estimates the firm-level employment effects of investment grants in Germany. In addition to the average treatment effect on the treated, we examine discrimination in the funding rules as a potential source of effect heterogeneity. We combine a staggered difference-in-differences approach with a matching procedure at the cohort level. The findings reveal a positive effect of investment grants on employment development. The subsample analyses yield strong evidence for heterogeneous effects based on firm characteristics and the economic environment. They highlight the responsibility of the local funding authorities to clarify ex ante which goals of a funding programme are most important in their regions.
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25.09.2025 • 29/2025
Fiscal policy will stimulate the East German economy next year – Economic Forecast Fall 2025 for the East German economy
In 2025, the economy in East Germany, as in Germany as a whole, is likely to do little more than stagnate. In the coming year, fiscal policy measures will stimulate the economy, but their effects are likely to be somewhat weaker than in Germany as a whole. The Halle Institute for Economic Research (IWH) expects the expansion rate of the East German economy in 2025 to be at 0.3%, slightly higher than that of Germany as a whole (0.2%). In both following years, it will rise to 1.1% and 1.2% respectively, which is slightly less than in the west.
Oliver Holtemöller
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25.09.2025 • 28/2025
Joint Economic Forecast Autumn 2025: Fiscal stimulus masks structural weakness
The German economy is emerging from the trough and is likely to regain some momentum over the next two years. Following stagnation in the first half of the year, the Joint Economic Forecast project group predicts gross domestic product growth of 0.2% for the current year in its fall report. In the next two years, an expansionary fiscal policy is likely to accelerate economic growth noticeably to 1.3% and 1.4%, respectively. This means that the institutes' forecast for this year and next remains roughly unchanged from the spring report. “The German economy is still on shaky ground,” says Dr Geraldine Dany-Knedlik, head of the Forecasting and Economic Policy Division at the German Institute for Economic Research (DIW Berlin). “It will recover noticeably in the next two years. However, given ongoing structural weaknesses, this momentum will not last.”
Oliver Holtemöller
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Climate Change Economics in Vietnam: Redefining Economic Impact
Christian Otto, Christoph Schult, Thomas Vogt
IWH Discussion Papers,
No. 15,
2025
Abstract
Vietnam, a lower-middle-income economy, faces severe climate risks from heat waves, sea-level rise, and tropical cyclones, which are expected to intensify under ongoing global warming. Using a dynamic general equilibrium model, we analyze economic transition dynamics from 2015 to 2100, incorporating heat-induced labor productivity losses, agricultural land loss, and cyclone-related property damage. We compare a Paris-compatible scenario limiting warming to below 2 °C with a high-emission scenario reaching 4–5 °C. While output and investment impacts remain highly uncertain and statistically indistinguishable across scenarios until 2100, consumption losses are significantly larger under high emissions, mainly driven by heat-related productivity declines, with cyclones contributing most to uncertainty. These findings underscore the importance of considering multiple impact channels beyond output damages in climate-development research.
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