Question

In a layout of a randomized block design with 7 treatments, each replicated 5 times, the needed 35 experimental units will be grouped into :

• A. 7 blocks of 5 plots each
• B. 5 blocks of 7 plots each
• C. 35 blocks of 1 plot each
• D. 1 block containing 35 plots

Hint:

In any standard RBD:
$\text{Number of Blocks} = \text{Number of Replications } (r)$
$\text{Number of Plots per Block} = \text{Number of Treatments } (t)$
This basic rule makes designing layouts straightforward.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
In a Randomized Block Design (RBD), the experimental field is partitioned into relatively homogeneous groups called "blocks".
The purpose of blocking is to minimize experimental error by grouping experimental units that are as similar as possible.
Detailed Explanation:
Let us review the structural rules of an RBD layout:
1. The number of blocks must be equal to the number of replications ($r$) of each treatment. Since each of the treatments is replicated 5 times, there must be 5 blocks.
2. Within each block, every treatment must appear exactly once. Since there are 7 treatments, each block must contain 7 plots (experimental units).
3. This setup ensures that the total number of experimental units is: \[ \text{Total units} = \text{Number of blocks} \times \text{Plots per block} = 5 \times 7 = 35 \] 4. Therefore, the 35 units are grouped into 5 blocks of 7 plots each.

Step 2: Final Answer:
The correct grouping is 5 blocks of 7 plots each, matching Option (B).