• Its power to determine causal relationship is much better that that of all other


  • The influence of extraneous variables can be more effectively controlled.
  • The element of human error is more reduced.
  • More conditions may be created and tested in this method.
  • This method yields generally exact measurements and it can be repeated.


  • It is very difficult to establish comparable control group and experimental group.
  • The scope of experimentation with human beings is extremely difficult
  • Experiment is often difficult to design as it tends to be expensive and time consuming
  • Experimentation can be used only in studies of the present but not in studies relating to the past or future


  • Experimentation is applicable to certain phenomena and certain social situations
  • Experimentation cannot be conducted if the independent variable cannot be manipulated.
  • This approach is generally suitable to ‘micro’ issues (involving interpersonal relationships) rather than to ‘macro’ situations (on account of the difficulty of manipulating institutions or social groups).


A variable is a changeable element in phenomena. Variables are divided in to two types

  • Independent Variable :is an experimental variable, which is manipulated in an experiment it is also known as causal variable.
  • Dependent Variable

            is a subject variable associated with control group. This is also known as effect or

      criterion variable.

Control Group

  • Control is central to experimental research.
  • This helps in distinguishing the experimental research from other methods of research.
  • Control group is that on which the experiments are not conducted. Control group helps in the process of comparison.
    •  Even the treatment is not applied to control group.


  • The measurement of dependent variable after the random assignment of subjects to experimental group and control group is called pretest


  • The measurement of dependent variable for experimental and control groups after the pretest and introduction of treatment is called posttest



Before – After or Pre test experimental design

  • This is normally called classical experimental design.
  •  It is more reliable and it represents the so-called four-cell design
  • Here, before experimentation all the groups are selected, observed and measured.
  • There is one independent variable - the treatment - and one dependent variable

After only or Post-test only experimental design

In this type of design the study is carried out under social conditions, which are not at all in the control of the physical or natural conditions

Quasi – Design or Post-facto experimental design

The name of the quasi experiment has been given to those situations in which the

experimenter cannot randomly assign subjects to experimental groups, but can still

manipulate the independent variable

Special design or Mixed design

This design demands as a pre-requisite, computer programme and the statistical consultant. This kind of mixed designing is used in a situation where the experimenter:

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