Page R3.1
R TUTORIAL, #3:
MEASURES OF CENTER
The (>) symbol indicates something that you will type in.
A bullet (•) indicates what the R program should output (and other comments).
TEST SCORES DATA SET
> Type: scores <- c(80, 76, 100, 83, 100)
> Type: scores
• Check to make sure you entered the values in correctly.
MEAN
• Find the mean of the scores.
> Type: mean(scores)
• You can also find the mean as follows:
> Type: sum(scores) / length(scores)
TRIMMED MEANS
> Type: mean(scores, trim=.2)
• This takes the trimmed mean of the data set after the top 20% and the
bottom 20% have been deleted. Here, the ‘76’ and one of the ‘100’s are
deleted.
MEDIAN
• Find the median of the scores.
> Type: median(scores)
