Regarding Difference-in-Difference, the main assumption is the parallel trend satisfication. Regarding the parallel trend test, just simply prove the joint null test of leads coefficients equalling to zero.However, there is another assumption of concern is "no anticipation effect". I read the paper of Borusyak, 2021 and I saw that he identified it in the Assumption 2 (page 8).

After running the test, I have the result is as below ( in this case I shift the actual event year to 3 years before. Array



tau0 represents the average estimate for relative year = -3, tau1 relative toyear = -2, ..., tau3 for relative year = 0

I do not know how to explain this result properly about whether the anticipation effect exists? Should we use the joint null test for tau0, tau1, and tau2?

(I did post a question about this previously but today I come up with a better and clearer version of this question)