A completely randomized
design is a type of Experimental
Design where the experimental
units are allocated to the treatments in
a completely random fashion.
Suppose we wanted to compare four brands
of washing powder and decide to carry out
for each brand.
We would prepare 16 apparently identical
pieces of soiled cloth and allocate them
to the powders at random. To do this we
might take 16 slips of paper and mark them
Brand 1#1 up to Brand 4#4. We would then
mix the pieces of paper up in a hat and
match a slip of paper drawn at random with
a piece of cloth also drawn at random.