+absence.google <- read.delim("absence_poll_data.tsv")
+colnames(absence.google) <- c("timestamp", "unique.name", "date.absent")
+absence.google$date.absent <- as.Date(absence.google$date.absent, format="%m/%d/%Y")
+absence.google$reported <- TRUE
+absence.google <- absence.google[,absence.data.cols]
+absence.google <- unique(absence.google)
+
+## combine the two absence lists and then create a unique subset
+absence <- rbind(missing.in.class[,absence.data.cols],
+ absence.google[,absence.data.cols])
+
+## these are people that show up in both lists (i.e., probably they
+## submitted too late but it's worth verifying before we penalize
+## them. i'd actually remove them from the absence sheet to suppress
+## this error
+absence[duplicated(absence[,1:2]),]
+absence <- absence[!duplicated(absence[,1:2]),]