Assumption Errors and Forecast Accuracy: A Partial Linear Instrumental Variable and Double Machine Learning Approach
Katja Heinisch, Fabio Scaramella, Christoph Schult
IWH Discussion Papers,
No. 6,
2025
Abstract
Accurate macroeconomic forecasts are essential for effective policy decisions, yet their precision depends on the accuracy of the underlying assumptions. This paper examines the extent to which assumption errors affect forecast accuracy, introducing the average squared assumption error (ASAE) as a valid instrument to address endogeneity. Using double/debiased machine learning (DML) techniques and partial linear instrumental variable (PLIV) models, we analyze GDP growth forecasts for Germany, conditioning on key exogenous variables such as oil price, exchange rate, and world trade. We find that traditional ordinary least squares (OLS) techniques systematically underestimate the influence of assumption errors, particularly with respect to world trade, while DML effectively mitigates endogeneity, reduces multicollinearity, and captures nonlinearities in the data. However, the effect of oil price assumption errors on GDP forecast errors remains ambiguous. These results underscore the importance of advanced econometric tools to improve the evaluation of macroeconomic forecasts.
Read article
Media Response
Media Response December 2025 Oliver Holtemöller: Mini-Aufschwung im kommenden Jahr wird wieder kleiner in: Handelsblatt, 12.12.2025 Oliver Holtemöller: Ökonomen rechnen mit…
See page
Archive
Media Response Archive 2021 2020 2019 2018 2017 2016 December 2021 IWH: Ausblick auf Wirtschaftsjahr 2022 in Sachsen mit Bezug auf IWH-Prognose zu Ostdeutschland: "Warum Sachsens…
See page
East Germany
The Nasty Gap 30 years after unification: Why East Germany is still 20% poorer than the West Dossier In a nutshell The East German economic convergence process is hardly…
See page
Policy Output
Reports › CompNet’s flagship and special reports provide in-depth, data-driven analysis on productivity, competitiveness, and related economic trends, using the latest CompNet…
See page
6th CompNet Annual Conference
Innovation, firm size, productivity and imbalances in the age of de-globalization 6 th CompNet Annual Conference, June 29-30, 2017, European Commission, Brussels, Belgium As the…
See page
7th CompNet Annual Conference
Economic Growth, Trade and Productivity Dispersion 7 th CompNet Annual Conference, June 21-22, 2018, Leopoldina, Halle (Saale), Germany The main target of this conference was to…
See page
7th vintage
7th Vintage CompNet Dataset The CompNet dataset includes a set of micro-aggregated indicators to enhance policy and academic analysis on competitiveness and productivity. All the…
See page
Conditional Macroeconomic Survey Forecasts: Revisions and Errors
Alexander Glas, Katja Heinisch
Journal of International Money and Finance,
November
2023
Abstract
Using data from the European Central Bank's Survey of Professional Forecasters and ECB/Eurosystem staff projections, we analyze the role of ex-ante conditioning variables for macroeconomic forecasts. In particular, we test to which extent the updating and ex-post performance of predictions for inflation, real GDP growth and unemployment are related to beliefs about future oil prices, exchange rates, interest rates and wage growth. While oil price and exchange rate predictions are updated more frequently than macroeconomic forecasts, the opposite is true for interest rate and wage growth expectations. Beliefs about future inflation are closely associated with oil price expectations, whereas expected interest rates are related to predictions of output growth and unemployment. Exchange rate predictions also matter for macroeconomic forecasts, albeit less so than the other variables. With regard to forecast errors, wage growth and GDP growth closely comove, but only during the period when interest rates are at the effective zero lower bound.
Read article
Financial Stability
Financial Systems: The Anatomy of the Market Economy How the financial system is constructed, how it works, how to keep it fit and what good a bit of chocolate can do. Dossier In…
See page
