Step 1: Understanding the Concept:
Replication is one of the three basic principles of experimental design (randomization, replication, and local control).
Step 2: Analyzing Each Option:
• (A) Reduces the error variance:
Replication increases the precision of estimates but does not directly reduce error variance.
It allows us to estimate error variance.
• (B) Ensures independence of the observations for drawing valid inferences:
Independence is ensured by randomization, not replication.
• (C) Provides an estimate of the error variance:
This is the primary purpose of replication.
By having multiple observations under the same treatment, we can estimate the variability due to experimental error.
• (D) Increases the accuracy of the estimates of the treatment effects:
While replication does increase precision, its main statistical purpose is to provide an estimate of error variance.
Step 3: Final Answer:
Therefore, option (C) is correct.