I found the bug.
Why in the world would .onAttach set the global digits option? This is
really bad coding practice.
.onAttach <- function(...) {
mylib <- dirname(system.file(package = "MatchIt"))
ver <- packageDescription("MatchIt", lib = mylib)$Version
builddate <- packageDescription("MatchIt", lib = mylib)$Date
cat(paste("## \n## MatchIt (Version ", ver, ", built: ", builddate, ")\n",
sep = ""))
cat("## Please refer to http://gking.harvard.edu/matchit for full
documentation \n",
"## or help.matchit() for help with commands supported by MatchIt.\n##\n",
sep="")
options(digits = 4)
}
