Which of the following techniques are used to control extraneous variables in research?

(A) Change of instrument

(B) Randomisation

(C) Matching

(D) Removing variables

(E) Changing the research method

Choose the correct answer from the options given below :

Key Points

Some techniques used to control extraneous variables in research are as follows:

• The technique of elimination – Simplest way to control the extraneous variables is to eliminate them from the research design.
• The constancy of condition – When extraneous variables cannot be controlled, they must be held constant throughout the experiment so that its effect is nullified easily. Holding homogenous values like age, gender, intelligence, etc naturally controls the effect of extraneous variables upon dependent variables.
• Randomization – It is a popular technique. In this technique, each member of the population or universe has an equal and independent chance of being selected. It randomly distributes the extraneous effects over the experimental and control conditions. 
• Balancing and Counterbalancing: These are other popular measures of controlling extraneous variables in research. 
• Matching subjects with random assignments: It is used for assigning subjects to groups to match individual subjects on extraneous variables.

Hence, Randomization, Matching, and Elimination are the correct answers.