Note on Introduction, Types of experimental research method.

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Experimental research method

The classical method used in physical sciences for many years is the experiment method. In the experiment method, the researcher exposed to control or hold all variable involved in the study at will. The usual approach is to hold all variables constant except one. By varying this one variable and monitoring changes in the output, the relationship between variable can be carefully studied and document.

Mathematically, the approach is used to the followingrelationship.


Where, y=dependent variable called output.


X’s=Independent variable called input.

Example: For instance, let y is the yield of a crop called output. The yield is affected by different independent variable say.

X1=Seed quality.

X2=amount of irrigation used.

X3=amount of manure used.

X4=The labour inputs.

Now keeping X1,X2,X3 constant we can observe the change in y as per unit in X4. The researcher can control X4 I,e he can vary X4 at his will. Such controlling is possible in physical vqriables however it is hardly so in case of variable associated with social phenomenon and human behavior.

Types of the experiment.

Broadly speaking , there are two types of experiment.

  1. Laboratory experiment.
  2. Field experiment.

Laboratory experiment.

Most of the experiment in physical sciences are done in laborities. If the research problem is such it is divorced from the real world surrounded it, laboratory experiment are to be carried out. A laboratory ca be considered as any setting in which the esearcher is able to closely control condition under which observations are made.

Two major feature of the laboratory experiment.

  1. In a lab experiment the researcher creats situations in which all the possible extraneous variable are controlled so that the variance produced by them are also controlled or kept to a minimum.
  2. Ina lab experiment the variable are manipulated and the effect of manipulation upon the dependent variable in examined.

The advantage of the laboratory experiment.

  1. It studies the problem in the pure uncontaminated and controlled situations so that the conclusion drawn is more dependable.
  2. It is replicable can be repeatedly proven.
  3. It has sufficient degree of interval validity.

The disadvantage of the lab experiment.

  1. It lacks external validity.
  2. It is costly as well as time taking.
  3. It is conducted inside the artificial situation of lab so it is far from the real life situation.

Field experiment.

In the field experiment, attempt are made to study the problem in its real setting and to minimize the influence of seemingly, unconnected variable. With the growth and development of statistics, the need for a special laboratory for the purpose of experimentation is no longer regarded as necessary for adequately controlled research. Replication, Randomization and use of certain statistical control methods help the conduction of field experiments with little inference from normal activity and with several variable being manipulated at one.

A feature of the field experiment.

  1. It is carried out in a more or less relastic situations. Thus if differs from a lab experiment which is carried out in the artificial situation or lab.
  2. Like lab experiment it is also manipulated the independent variable and controls the extraneous (irrelevant) variable.
  3. A field experiment manipulates the variable under as carefully controlled condition as the situation permits.

Advantage of field experiment

  • It deals with realistic life situation , hence it is more suited of studying social changesd , social processes and social influences.
  • The principal of research is that the more reliable the situation the stroinger is the effect of the variables under study. In a field experiment this principle is fully satisfied.
  • The variables are stronger in a case of experimental research of more realistic situation , so researcher can make better and sound generalization.

Disadvantage of field experiment

  • Since it is carried out in a realistic situation there is always the possibility that the effect of independent variables is contaminated with uncontrolled environmental variables.
  • In a field experiment, it is not possible to achieve a high degree of accuracy.
  • A field experiment requires that the investigator ha s high social skill to deal effectively with people in a field situation.

Experimental group of controlled group

Both in job and field experiment the extraneous variables should be controlled . There are several ways of manipulating and controlling the variables. One of the most common methods is the use of pre experimental instruction. In this method the total group under study is divided into two groups. One group is experimentally treated or experimental treated should be given to one group which Is called the experimental group, second group is kept constant or controlled or without any experimental treatment . Then after sometime the difference between these two group is obtaines which shows the effectiveness of programme.

EX- post facto research

Sometimes in many situations it takes a long time to conduct a research . also it is practically not possible to conduct a research on same subject for a long time. So the method of ex-post facto is used in these situations where researcher draws some conclusion of the basic of past activities.

Ex-post facto is an attempt to trace the past activities . In this method past activities are analyzed in present and some conclusion are drawn which may be useful for present and planning for the future.


Ex-post facto research is a systematic empirical inquiry in which the researcher doesn’t have anydirect control iver independent variables, because their manifestations have alrerady occurred or because they are inherently not manipulative . Inferences about the relation variables are therefore made without direct intervention from concomitant variation independent variables .

Examples, The ex-post facto technique generally moves from present to future , suppose, it is proposed to stuidy the study the influences of boarding and non-boarding schools education upon future adjustability of the students. We take an equal number of students in two groups , one group consisting of on type of education and other consisting of other type of education. The groups are selected keeping in mind that pother variables like age , economic status , intelligence are matched in both cases.

After ten years (say) we shall again try to locate those persons and see how they are placed in life. The difference betrween the groups may be attributed tro the nature of education received.

But , since it is often very difficult to locvate persons after sufficenrt period of time , the observation is made from present to past . Mr chaplin studied the relation between scouting training and delinquency by using this met5hod. For this purpiose he took matchged samples from older boys – one consisiting of delimquents and other consisiting of non- delinquents . These two samples were similar in all respects . Them he tired to find how many among the two groups have scout training.


Kerlinger, F.N. Foundation of Behavioural Research. New Delhi: Surjeet Publication, 2000.

Kothari, C.R. Research Methodology. India: Vishwa Prakashan, 1990.

Singh, M.L. and J.M Singh. Understanding Research Methodology. 1998.

Singh, Mrigendra Lal. Understanding Research Methodology. Nepal: National Book centre, 2013.

  1. The classical method used in physical sciences for many years is the experiment method.
  2. Most of the experiment in physical sciences are done in laboratories.
  3. In the field experiment, the attempt is made to study the problem in its real setting and to minimise the influence of seemingly, unconnected variable.
  4. Ex-post facto research is a systematic empirical inquiry in which the researcher doesn’t have any direct control over independent variables, because their manifestations have already occurred or because they are inherently not manipulative .

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