In this method variables beings studied are controlled by the investigator. In other the effect of one variable is observed while other relevant variables are held constant.

This methods includes field experiment as well as laboratory experimentation. In field experiment the study is conducted b comparing experimental group with the control group. In laboratory experiment the investigator creates a situation with the exact conditions he wants to have and in which he controls some and manipulates other variables. He then observes and measures the effect of the manipulation of the independent variables on the dependent variables in a situation in which the operation of other relevant factors is held to a minimum.