1% generated by tables/make_tables.py from /Users/simon-pierreboucher/Desktop/UQO/Recherche/Recherche-UQO/informatique/wp44/results/econometrics/breaks.csv2\begin{longtable}{lrrrrrrrrrrrr}3\caption{Structural-change estimates for the nine AI categories: interrupted-time-series level and slope changes at 2022-12 (ChatGPT), level changes at the alternative event dates 2023-04 (GPT-4) and 2024-09 (o1), placebo p-values, and Bai--Perron and PELT break dates.}\label{tab:ai_breaks}\\4\toprule5\textbf{Category} & \textbf{Level 2022-12} & \textbf{p} & \textbf{Slope 2022-12} & \textbf{p } & \textbf{Level 2023-04} & \textbf{p } & \textbf{Level 2024-09} & \textbf{p } & \textbf{Placebo p (level)} & \textbf{Placebo p (slope)} & \textbf{Bai--Perron (BIC)} & \textbf{PELT} \\6\midrule7\endfirsthead8\toprule9\textbf{Category} & \textbf{Level 2022-12} & \textbf{p} & \textbf{Slope 2022-12} & \textbf{p } & \textbf{Level 2023-04} & \textbf{p } & \textbf{Level 2024-09} & \textbf{p } & \textbf{Placebo p (level)} & \textbf{Placebo p (slope)} & \textbf{Bai--Perron (BIC)} & \textbf{PELT} \\10\midrule11\endhead12Large language models & 0.106 & 0.075 & 0.034 & 0.000 & 0.236 & 0.002 & 0.457 & 0.001 & 0.938 & 0.200 & 2022-07-01 & 2023-10 \\13Foundation models & -0.075 & 0.340 & 0.006 & 0.021 & 0.023 & 0.756 & 0.084 & 0.173 & 0.692 & 0.246 & 2021-10-01 & 2020-02; 2023-10 \\14Multimodal AI & 0.025 & 0.600 & 0.024 & 0.000 & 0.150 & 0.002 & 0.330 & 0.001 & 0.969 & 0.200 & 2022-04-01 & 2020-12; 2023-12 \\15Generative AI & 0.036 & 0.556 & 0.019 & 0.000 & 0.150 & 0.017 & 0.324 & 0.000 & 0.969 & 0.308 & 2021-11-01 & 2020-12; 2023-12 \\16AI agents & -0.210 & 0.028 & 0.040 & 0.000 & -0.151 & 0.090 & 0.226 & 0.003 & 0.631 & 0.400 & 2022-07-01; 2024-07-01 & 2023-12; 2025-08 \\17Reinforcement learning & -0.164 & 0.013 & 0.012 & 0.000 & -0.158 & 0.006 & 0.054 & 0.071 & 0.615 & 0.385 & 2021-07-01; 2024-12-01 & 2021-01; 2024-12 \\18ML theory & -0.080 & 0.090 & 0.009 & 0.000 & -0.047 & 0.296 & 0.081 & 0.026 & 0.662 & 0.215 & 2020-05-01; 2022-07-01 & 2020-02; 2023-12 \\19DL architectures & -0.071 & 0.126 & -0.002 & 0.136 & -0.051 & 0.260 & 0.008 & 0.792 & 0.400 & 0.708 & 2021-07-01 & 2020-02; 2023-12 \\20AI safety and alignment & -0.206 & 0.002 & 0.016 & 0.000 & -0.080 & 0.244 & 0.150 & 0.010 & 0.446 & 0.308 & 2021-06-01; 2022-09-01 & 2020-02; 2024-02 \\21\bottomrule22\multicolumn{13}{p{0.95\linewidth}}{\footnotesize Monthly log counts, seasonally adjusted; HAC p-values (Part IV, Section~\ref{sec:m-its}). Level changes are in log points of the monthly count; slope changes in log points per month. Placebo p-values are the share of placebo event dates (Section~\ref{sec:m-placebo}) whose t-statistic exceeds the true one. Bai--Perron dates: breaks selected by BIC with trimming h=15 months; PELT: penalised exact linear-time change points. The categories are multi-label, so the series overlap.}\\23\end{longtable}24