This note discusses the interpretation of event-study plots produced by recent difference-in-differences methods. I show that even when specialized to the case of non-staggered treatment timing, the default plots produced by software for several of the most popular recent methods do not match those of traditional two-way fixed effects (TWFE) event-studies. The plots produced by the new methods may show a kink or jump at the time of treatment even when the TWFE event-study shows a straight line. This difference stems from the fact that the new methods construct the pre-treatment coefficients asymmetrically from the post-treatment coefficients. As a result, visual heuristics for evaluating violations of parallel trends using TWFE event-study plots should not be immediately applied to those from these methods. I conclude with practical recommendations for constructing and interpreting event-study plots when using these methods.

翻译：本说明讨论了近期双重差分方法生成的事件研究图的解读问题。研究表明，即使专门针对非交错处理时点的情况，当前多种主流新方法的默认软件输出图与传统双向固定效应事件研究图仍存在差异。当TWFE事件研究图呈现直线趋势时，新方法生成的图示可能在处理时点处显示拐点或跳跃。这种差异源于新方法对处理前系数与处理后系数的不对称构建方式。因此，基于TWFE事件研究图评估平行趋势假设的视觉启发准则不应直接套用于这些新方法的图示。最后，本文就使用这些方法时构建和解读事件研究图提出了实践建议。