This content will become publicly available on September 1, 2027

Title: GDP Forecasting for the United States (2025–2030) Using ARIMA, OLS, LSTM and Hybrid Models
Reliable GDP forecasting plays a critical role in macroeconomic management, particularly during periods of heightened uncertainty such as the 2008 financial crisis and the 2020 pandemic shock. During these episodes, timely GDP projections provided policymakers with essential guidance for assessing recession depth, calibrating emergency fiscal and monetary responses, and preventing further macroeconomic deterioration. To support policy evaluation and medium-term growth planning, this study applies a unified forecasting framework to annual U.S. GDP data from 1980 to 2024 using three representative base models—ARIMA, OLS, and LSTM—together with a linear hybrid ensemble that combines their predictions. Each base model is paired with preprocessing tailored to its statistical assumptions. For ARIMA, unit-root testing confirms non-stationarity, and second-order differencing produces a stationary series, leading to the selection of an ARIMA (0,2,2) specification via information criteria and autocorrelation diagnostics. For OLS, a log-linear specification stabilizes exponential growth, yielding an estimated long-run annual trend of approximately 4.98%. For LSTM, the log-transformed series is normalized and converted into four-year sliding window sequences to enable nonlinear temporal learning despite the limited sample size. The hybrid ensemble—implemented as a convex linear blend of the three base forecasts estimated by least squares—is designed to exploit complementary strengths across linear and nonlinear components. All models generate forecasts for 2025–2030 and are evaluated using MAE, RMSE, MAPE, MASE, and Theil’s U. The empirical results show that the hybrid ensemble (COLBA) model achieves the lowest MAE, RMSE, MASE, and Theil’s U, while the standalone ARIMA model attains the smallest MAPE. These findings indicate that combining statistically grounded econometric models with neural networks can modestly improve overall accuracy even when only annual data are available, while ARIMA remains particularly effective for preserving proportional accuracy in trend-dominated macroeconomic series.  more » « less
Award ID(s):
2100134 2209637 2234911 2417608
PAR ID:
10711414
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
Avestia Publishing, International ASET Inc.
Date Published:
Format(s):
Medium: X
Location:
London, United Kingdom
Sponsoring Org:
National Science Foundation
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