Difference between CRD and RBD

Complete Random Design (CRD)

In CRD, as the name suggests, treatments are assigned completely randomly so that each treatment unit gets the same chance of receiving any one treatment. This is suitable only for the experiments such as laboratory experiments or green house studies etc, where the experiment material is homogeneous and not for heterogeneous studies. In replication category, CRD differs from treatment to treatment i.e, 4 to 5 replications are sufficient.

Advantages:

• It is simple and easy.
• It provides the maximum number of degrees of freedom.

Disadvantages:

• It is less accurate than other designs.
• It reduces precision.
• It increases experimental errors.

Randomized Block Design (RBD)

In RBD, materials are assigned to homogeneous sub-groups which is named as a block. It comes in the category of single factor design. The analysis is easy but becomes complicated when the missing plot technique is required.  In replication category, RBD differs from treatment to treatment i.e, 4 to 5 replications are sufficient.

Advantages:

• The efficiency level is more than CRD.
• It reduces experimental errors.
• It increases precision.

Disadvantages-

• It is not suitable for a larger number of treatments.
• Analysis is easy but becomes complicated when the  missing plot technique is required.

Difference between CRD and RBD:

	CRD	RBD
Layouts	The whole field is divided directly into plots (product of replications=treatments).	The field is divided into homogeneous i.e, plots=number of treatments.
Conditions of Use	The amount of experimental material to be used is tested and the nature of the fertility variation of the field.	The fertility variation usage moves in one direction.
Randomization	In CRD, treatment-wise.	In RBD, replication or block-wise.
Local Control	Not adopted in this case.	In this case, adopted by homogeneous blocks.
Components of Variation	Divided into 2 component divisions.	Divided into 3 component divisions.
Analysis	Analysis in CRD is very easy and simple.	In this case, analysis is easy but becomes complicated if the missing plot technique is applied.
Accuracy	CRD is less accurate than other designs.	The accuracy level of RBD is greater than CRD.
Efficiency	CRD is not that efficient when compared to RBD.	RBD is very efficient than CRD.