1% generated by tables/make_tables.py from ./results/econometrics/breaks.csv2\begin{table}[htbp]\centering\caption{Structural change at 30 November 2022 in the nine AI categories: interrupted-time-series level and slope changes, placebo p-values, Bai--Perron and PELT break dates.}\label{tab:ai_breaks}3\begin{threeparttable}\small4\begin{tabular}{lrrrrrrrr}5\toprule6\textbf{Category} & \textbf{Level} & \textbf{p (level)} & \textbf{Slope} & \textbf{p (slope)} & \textbf{Placebo p (level)} & \textbf{Placebo p (slope)} & \textbf{Bai--Perron} & \textbf{PELT} \\7\midrule8LLM & 0.106 & 0.075 & 0.034 & 0.000 & 0.938 & 0.200 & 2022-07 & 2023-10 \\9Foundation & -0.075 & 0.340 & 0.006 & 0.021 & 0.692 & 0.246 & 2021-10 & 2020-02; 2023-10 \\10Multimodal & 0.025 & 0.600 & 0.024 & 0.000 & 0.969 & 0.200 & 2022-04 & 2020-12; 2023-12 \\11Generative & 0.036 & 0.556 & 0.019 & 0.000 & 0.969 & 0.308 & 2021-11 & 2020-12; 2023-12 \\12Agents & -0.210 & 0.028 & 0.040 & 0.000 & 0.631 & 0.400 & 2022-07; 2024-07 & 2023-12; 2025-08 \\13RL & -0.164 & 0.013 & 0.012 & 0.000 & 0.615 & 0.385 & 2021-07; 2024-12 & 2021; 2024-12 \\14ML theory & -0.080 & 0.090 & 0.009 & 0.000 & 0.662 & 0.215 & 2020-05; 2022-07 & 2020-02; 2023-12 \\15DL arch. & -0.071 & 0.126 & -0.002 & 0.136 & 0.400 & 0.708 & 2021-07 & 2020-02; 2023-12 \\16AI safety & -0.206 & 0.002 & 0.016 & 0.000 & 0.446 & 0.308 & 2021-06; 2022-09 & 2020-02; 2024-02 \\17\bottomrule18\end{tabular}19\begin{tablenotes}\footnotesize\item Monthly log counts, seasonally adjusted; HAC p-values (Part IV, Section~\ref{sec:m-its}). Level change in log points of the monthly count at 2022-12; slope change in log points per month. Placebo p-values: share of placebo event dates (Section~\ref{sec:m-placebo}) whose t-statistic exceeds the true one. Bai--Perron: break months selected by BIC with trimming h = 15 months; PELT: penalised exact linear-time change points. Categories are multi-label, so the series overlap. Category abbreviations as in Table~\ref{tab:ai_growth}.\end{tablenotes}20\end{threeparttable}\end{table}21