We examine the uptake and measurable effects of GPT-assisted writing in economics working paper abstracts. Focusing on the IZA discussion paper series, we detect a significant stylistic shift following the public release of ChatGPT-3.5 in March 2023. This shift appears in core textual metrics—including mean word length, type-token ratio, and readability—and reflects growing alignment with machine-generated writing. While the release of ChatGPT constitutes an exogenous technological shock, adoption is endogenous: authors choose whether to incorporate AI assistance. To capture and estimate the magnitude of this behavioral response, we combine stylometric analysis, machine learning classification, and prompt-based similarity testing. Event-study regressions with fixed effects and placebo checks confirm that the observed shift is abrupt, persistent, and not attributable to pre-existing trends. A similarity experiment using OpenAI’s API shows that post-ChatGPT abstracts more closely resemble their GPT-optimised counterparts than do pre-ChatGPT texts. A classifier trained on these variants achieves 97% accuracy and increasingly flags post-March 2023 abstracts as GPT-like. Rather than indicating wholesale substitution, our findings suggest selective human–AI augmentation in professional writing. The framework introduced here generalises to other settings where writing plays a central role—including resumes, job descriptions, legal briefs, research proposals, and software documentation.
Paper: https://www.iza.org/publications/dp/18062/the-behavioral-signature-of-genai-in-scientific-communication
Category: Economics
Toll Index June 2025
The Toll Index was first proposed in IZA DP5522 which was published in the Journal of Forecasting. It has been widely covered in national and international media (selection):
Focus Magazin,
Tim Harford – The undercover economist,
Financial Times,
MoneyWeek,
WirtschaftsWoche,
CNN International,
DRS3 Swiss public radio,
Deutsche Welle.
The Toll index was redefined in 2024 to account for various toll-related policy changes like including lighter trucks in the system or adding roads to the toll road network.
Citation: “Nowcasting business cycles using toll data.” Journal of Forecasting 32:4 (2013): 299–306(with K. F. Zimmermann).
Toll Index May 2025
The Toll Index was first proposed in IZA DP5522 which was published in the Journal of Forecasting. It has been widely covered in national and international media (selection):
Focus Magazin,
Tim Harford – The undercover economist,
Financial Times,
MoneyWeek,
WirtschaftsWoche,
CNN International,
DRS3 Swiss public radio,
Deutsche Welle.
The Toll index was redefined in 2024 to account for various toll-related policy changes like including lighter trucks in the system or adding roads to the toll road network.
Citation: “Nowcasting business cycles using toll data.” Journal of Forecasting 32:4 (2013): 299–306(with K. F. Zimmermann).
Toll Index April 2025
The Toll Index was first proposed in IZA DP5522 which was published in the Journal of Forecasting. It has been widely covered in national and international media (selection):
Focus Magazin,
Tim Harford – The undercover economist,
Financial Times,
MoneyWeek,
WirtschaftsWoche,
CNN International,
DRS3 Swiss public radio,
Deutsche Welle.
The Toll index was redefined in 2024 to account for various toll-related policy changes like including lighter trucks in the system or adding roads to the toll road network.
Citation: “Nowcasting business cycles using toll data.” Journal of Forecasting 32:4 (2013): 299–306(with K. F. Zimmermann).
Toll Index February 2025
The Toll Index was first proposed in IZA DP5522 which was published in the Journal of Forecasting. It has been widely covered in national and international media (selection):
Focus Magazin,
Tim Harford – The undercover economist,
Financial Times,
MoneyWeek,
WirtschaftsWoche,
CNN International,
DRS3 Swiss public radio,
Deutsche Welle.
The Toll index was redefined in 2024 to account for various toll-related policy changes like including lighter trucks in the system or adding roads to the toll road network.
Citation: “Nowcasting business cycles using toll data.” Journal of Forecasting 32:4 (2013): 299–306(with K. F. Zimmermann).
Toll Index January 2025 | -2.6% year over year
The Toll Index was first proposed in IZA DP5522 which was published in the Journal of Forecasting. It has been widely covered in national and international media (selection):
Focus Magazin,
Tim Harford – The undercover economist,
Financial Times,
MoneyWeek,
WirtschaftsWoche,
CNN International,
DRS3 Swiss public radio,
Deutsche Welle.
The Toll index was redefined in 2024 to account for various toll-related policy changes like including lighter trucks in the system or adding roads to the toll road network.
Citation: “Nowcasting business cycles using toll data.” Journal of Forecasting 32:4 (2013): 299–306(with K. F. Zimmermann).
Flash IZA/Fable SWIPE Consumption Index at over +7% in February 2025
The 14-day month-to-date data for February 2025 shows a 7% year-over-year increase in consumption.
This initial “flash estimate” compares the first 14 days of February 2025 with the same period in February 2024 and should not be interpreted as the final year-over-year figure for February. As new data arrives daily, we will calculate 15-day, 16-day, and subsequent month-to-date partials until a stable value is reached, typically about three days into March. Stay tuned, and follow daily updates via the embedded live graph or at https://fable.radar.iza.org.
Note: The inflation-adjusted SWIPE index in the graph above assumes February 2025 inflation matches January 2025 levels.
Linke to Paper: The IZA/Fable Swipe Consumption Index