Diagnostics and Quality Checks

Outlier Flag

Check Distance From Center

Outlier checks identify observations that sit far away from the usual values.

Program

Play the script to change the distance limit and see how many values are flagged.

outlier_flag.R 
limit <- 
value <- c(42, 44, 43, 58)
center <- median(value)
distance <- abs(value - center)
flagged <- distance > limit
count <- sum(flagged)
label <- paste("outliers", count, sep = ":")
cat(label, "\n", sep = "")

limit <- 
value <- c(42, 44, 43, 58)
center <- median(value)
distance <- abs(value - center)
flagged <- distance > limit
count <- sum(flagged)
label <- paste("outliers", count, sep = ":")
cat(label, "\n", sep = "")

limit <- 
value <- c(42, 44, 43, 58)
center <- median(value)
distance <- abs(value - center)
flagged <- distance > limit
count <- sum(flagged)
label <- paste("outliers", count, sep = ":")
cat(label, "\n", sep = "")
center `median(value)` gives a robust center for the values.
distance `abs(value - center)` measures how far each value is from the center.
flag `distance > limit` marks unusually distant observations.