We limit the number of years included in our analysis of
each accounting standard event to (1) reduce sampling
bias from including all years in the estimations and (2)
strengthen the generalizability of our results. Our sample
period for each accounting standard includes the four-year
period that ends two years before and the four-year period
that begins two years after the implementation of each
standard (eight years in total).14 The year of implementation,
the preceding year, and the following year are excluded
to avoid adoption year effects. Given the long time period
over which standards are implemented, different years’ data
are relevant for different standards. This serves to randomize
the effects of non-accounting effects across the tests