dataprep.out = dataprep(
  foo = texas,
  predictors = c("income", "ur", "poverty"),
  predictors.op = "mean",
  time.predictors.prior = c(1985:1993),
  special.predictors = list(
    list("bmprison", c(1990,1992,1991,1988), "mean"),
    list("alcohol", 1990, "mean"),
    list("aidscapita", c(1990,1991), "mean"),
    list("bmprison", c(1988,1990:1992), "mean"),
    list("alcohol", 1990, "mean"),
    list("aidscapita",  1990:1991, "mean"),
    list("black", 1991:1992, "mean"),
    list("perc1519", 1990, "mean")),
  dependent = "bmprison",
  unit.variable = "statefip",
  unit.names.variable = "state",
  time.variable = "year",
  treatment.identifier = 48,
  controls.identifier = statefiplist[!statefiplist %in% 48],
  time.optimize.ssr = 1985:1993,
  time.plot = 1985:2000
)

synth.out = synth(dataprep.out)
placebos = generate.placebos(dataprep.out, synth.out)