Experimental Design in Research | Quick Guide

Experimental design in research, In this tutorial we are going to discuss what are the requirements of a good experimental design.

There are three requirements of a good Experimental Design in Research,

  1. Randomization
  2. Replication
  3. Local Control

Experimental Design in Research

Let us understand each points (Randomization, Replication and Local Control) in a detailed way.

Principal component analysis (PCA) in R »

What do you understand by randomization in experimental design?

The allocation of treatments to experimental units in such a manner that an experimenter unit has an equal chance of receiving any of the treatments is called randomization.

The total number of units in an experiment is always equal to the sum of the replicates of all the treatments selected.

What is the role of randomization in the experimental process?

If we include randomization in experimental design then many advantages are there.

  • It eliminates human biases.
  • Randomization enables the experiment free from any systematic influences of the environment.
  • The process of randomization enables the to apply mathematical theories which would have otherwise not been possible.
  • If we include randomization in the process, introduce the independence in the assignment of treatments to the experimental units. So ultimately help to create independence in experimental errors.
  • Last but not least, randomization in experimental designs is one of the required conditions to attach a probability statement to the estimated treatment differences.

Naive Bayes Classification in R » Prediction Model »

What is mean by replication?

Repetition of a treatment on a number of experimental units under similar conditions is called replication.

  1. Replication is essential to obtain a valid estimate of the experimental error variance.
  2. Replications are required to attach a probability statement with estimated treatment differences.
  3. The larger number of replications reduces the standard error of the treatment means.
  4. The average performance of the treatment is better assessed by way of replications.

Completely Randomized Experimental Design »

What do you understand by local control?

Local control is a device to maintain greater homogeneity of experimental units within a block of an experiment or as a whole.

Local control is also known as error control. It contributes a lot to increase the efficiency of an experiment.

  • Local control reduces the experimental error and able to makes efficient designs.
  • It makes any test of significance more powerful and sensitive.
  • Its ability to help identify the small differences in the treatments.


Experimental design means creating a set of guidelines to test a hypothesis. A good experimental design requires a strong understanding of the process you are working on.

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