Research Design

Replication• Repetition of the basic

experiment• See if units respond the same

way to the same treatment• Significance of the results can be

tested• Number of replicates depends

on 1. Degree of precision required2. Degree of homogeneity of the

sample3. Number of treatments in the

study

Randomization

• Chance assignment of experimental units to the treatment or vice-versa

• Assures valid and unbiased estimates of means and differences between treatments

• Test for significance is valid

Local control

• Balancing grouping and blocking of experimental units in the experimental design

• Blocking – assignment of units to a block to ensure that the block is homogeneous

5

128 14

15

4

10 11

2 3

913

1 76

- Control 1% 5% 10% + Control

8 9 13 1 5

12 3 11 2 8

6 14 4 7 10

Block Experimental Subjects

A

B

C

1 2 3

76 8

11

12

13

4 5

910

14

15

- Control 1% 5% 10% + Control

1 4 2 3 5

9 8 7 6 10

14 15 13 12 11

Group Exercise1. Identify dependent, independent, and

extraneous variables.2. Enumerate the treatments given.3. How many replicates were used?4. How many samples were used in the project? How

were these chosen from the population?

5. Which type of research design (CRD or RCBD) was chosen or was most appropriate for the project. Why?

Bonus: What was the test of significance used?

Group ExerciseGroups 1 and 2 – Comparative analysis of the effects of

VCO and olive oil on the cholesterol levels in rabbitsGroups 3 and 4 – Utilization of blood of stray dogs as a

component of blood agar platesGroups 5 and 6 – Formulation of an all-organic nutrient

solution for lettuceGroups 7 and 8 – Mango seed kernels as an alternative

source of starch in flourGroups 9 and 10 – Lecithin organogels as a topical aid of

green tea extracts for the treatment of inflammatory skin disease