Page 283 - Area 9 - Relevant Document

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Disadvantages:

1. There is no restriction involved in randomization so accuracy of
results is adversely affected.
2. This design has a limited application.
3. His design is seldom used under field conditions because of the
inability to control or check other sources of variability which could
increase the size of the experimental error.

RANDOMIZATION IN THE EXPERIMENTAL LAY OUT.

 Randomization is done throughout the experimental units.
 Randomization is done just once by using any of the three methods.
Example: a study with 4 treatments and replications

Methods of randomization which maybe employed are: drawing cards, draw
lots, use of the table of Random numbers.

RANDOMIZATION BY DRAWING CARDS

 Easy and convenient and most applicable to treatments even with
`3 treatments.

 An Experiment with 4 treatments (A,B,C,D or 1,2,3,4 and 4
replications.
 Experimental Units = 4 x 4 = 16 EU’s
 STEPS:
1. Start by shuffling the cards thoroughly and from top to
bottom of the pack, draw 16 pieces of cards at random to
represent the EU’s.
2. List down the number of draws in sequences from 1 – 16 as
shown.
3. Assign ranks to the number in the cards as indicated in case
the same number of different suits are drawn, the earlier
draws must be given a lower rank number. . See ranking
and treatment assignments in the figure below.

Sequence Number Rank Assignment
1 6 7 A
2 9 12 A
3 2 3 A
4 4 5 A
5 10 15 B
6 8 11 B
7 6 8 B
8 10 16 B
9 1 1 C