Thank you for this. Wondering what do we consider a good test of parallel tends? Have seen papers test to see if pre intervention point estimates are different and concluding trends are same even if there's a clear pattern in pre trend point estimates increasing or decreasing.
Totally working on this problem now with @ambilinski ! Our preprint is up on arXiv arxiv.org/abs/1805.03273 My bottom line is that I don't think tests of parallel pre-trends are very useful at all (they have little to do w/counterfactuals)