importFrom(lpSolve, lp)
importFrom(utils, packageDescription)
importFrom("grDevices", "dev.off", "postscript")
importFrom("graphics", "lines", "plot")
importFrom("stats", "complete.cases", "delete.response", "lowess", 
           "model.frame", "model.matrix", "na.fail", "na.omit", "terms",
           "update.formula")
importFrom("utils", "read.table")
importFrom("Zelig", "zelig_setx_to_df")
export(whatif)
S3method(plot, whatif)
S3method(summary, whatif)
S3method(print, whatif)
S3method(print, summary.whatif)
