  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 three of the most popular recent methods (de Chaisemartin and
D'Haultfoeuille, 2020; Callaway and SantAnna, 2021; Borusyak, Jaravel and
Spiess, 2024) do not match those of traditional two-way fixed effects (TWFE)
event-studies: 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 analyzing 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.
