Stat 101L: Lecture 20
1
1
Randomization
Randomization tends to spread the
effects of uncontrolled outside
variables evenly across the
treatment groups.
Randomization reduces the chance
that an uncontrolled outside
variable will bias the results.
2
Replication
Within an experiment.
–must have several experimental
units in each treatment group.
–can assess the natural variation
in the response for units treated
the same.
3
“Replication”
Repeating the entire experiment.
–This is especially important if the
subjects in an experiment are not a
random sample fro m a population.
–Are the r esults of the entire
experiment repeatable?
