does the heavy lifting for computing the attcpo
compute.attcpo(Y1t, Y0tmin1, Y0tmin2, Y0tqteobj, h = NULL, ytmin1seq = NULL,
yseqlength = NULL, se = TRUE, iters = 100, method = "level")
treated group outcomes in period t
treated group outcomes in period t-1
treated group outcomes in period t-2
qte object to get counterfactual quantiles from
optional bandwidth
optional sequence of values to compute attcpo(y') for
optional length of sequence of values to compute attcpo(y') for; default is 100
boolean for whether or not to compute standard errors
number of bootstrap iterations to use to compute standard errors
can be "level" or "rank", whether the conditional expectation is based on the level of Y0tmin1 or its rank