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RULE NO. 5. Administer all cultural and management practices as
uniform as possible except the experimental treatments.

In experiments involving farm animals the blocks to use maybe sex,
breed, size or weight , age of the animals.

STATISTICAL ANALYSIS
Analysis of Variance is similar to CRD except with the addition of one
more source of variation, the block.
Example: Grain yield of corn grown from 5 population densities
replicated 4 times. (Gomez et. Al 1976)
Population BLOCKS TOTAL MEAN
density I II III IV

10,000/ha 2.1 2.5 3.2 3.6 11.3 2.63

15,000/ha 4.0 3.9 4.3 4.5 16.7 4.18

20,000/ha 4.9 5.1 5.5 6.1 21.6 5.40

30,000/ha 2.9 3.1 3.2 4.4 13.6 3.40

TOTAL 17.5 19.4 24.4 83.2 4.16

STEP 1.Organize the data and tabulate them . Determine the sum and
mean horizontally for treatments , the sum vertically for blocks and the
grand total as shown in the above table.

STEP 2. Compute for the degrees of freedom ( df) values for the various
sources of variation (SV). Thedf is divided into 3 parts, the block degrees of
freedom (Bdf) ,treatment degrees of freedom (tdf) and the Error Degrees of
freedom (Edf)

Tdf = rt – 1 = 4 (5) – 1 = 20 – 1 = 19
Bdf = r – 1 = 4 – 1 = 3
tdf = t – 1 = 5- 1 = 4
Edf = Tdf–(Bdf + tdf ) = 19 – (3 + 4) = 12

STEP3. Compute the various Sum of Squares ( SSs

2
2
CF = (GT) =(83.2) = 346.11
rt 4(5)
TSS = X – CF
2
= (2.1) + (2.5) +…………..+ (4.4) - CF
2
2
2
371.5 – 346.11 = 25.39