Difference Between Internal & External Validity for Research

02/11/2020 | George Orwell | 806

What is Validity in Research?

Validity is basically a concept that is utilized for testing the relationship between cause and effect. It is all about the accuracy and consistency of measures. Validity in research can be categorized into two, these are internal and external validity. These are basically two concepts that are applied for ensuring that the outcome of the investigation can be trusted and it contains meaning.

For Example: when temperature of water is measured at regular interval of time in same situation. The tool used for measuring the temperature of water shows the different temperatures every time. If in a case when an individual has properly controlled the situation for making sure that temperature remains similar. It is considered to be a tool used for measuring the temperature of the water is defective and therefore, measurement is invalid. If a tool used for measuring temperature shows the different temperature each time then measurement can be considered to be as highly valid.

What is internal validity?

Internal validity is the technique to measure the effectiveness of research. It is mainly concerned with a way research procedure has been performed by the researcher. Internal validity can be considered to be as your research report containing the proof that the design you have selected for research represents the things that have been actually observed. Internal validity can also be referred to as extend up to which outcome of the investigation could be generalized.

Example: A person has developed special type of application for reducing the bad mood. Researcher has select participants by using random sampling technique. One group task is  to utilize the application and  other team is responsible for controlling the activities. Person performing  research has confirm the elimination of biasness in formation of group. Researcher need to measure different components such as economic and social status of participants, age , gender etc. along with mood.

Importance of internal validity

Internal validity is very much crucial as without it there is no relationship between cause and effect that can be developed.

How to measure internal validity

You can make a comparison between the responses provided by participants with that of the purpose of investigation. For example, you can make a comparison between self-reported amounts of cigar smoking with the special purpose of measuring the cutinize level in breath. The investigation performed by you would be considered to be highly valid if you will be able to provide a proper explanation of findings.

What is external validity?

External validity links to the applicability of the findings drawn from the investigation in real-life situations. It can be referred to as extend up to which conclusion drawn from a particular investigation procedure could be made applicable in other circumstances. For example, if the findings are applicable to other circumstances then in such case investigation in highly valid.

Example: Using the same example given in internal validity, but this time investigator has permitted participants for utilizing the specific application at their homes. Investigator need to clearly define the population and  give the justification for selecting a representative sample which indicates research is highly externally valid.


Importance of external validity

External validity is crucial as if in case the cause is address but still, you will not be able to generalize your findings. It is the type of validity that could be enhanced by facilitating experiments in more natural arrangements and also by utilizing the random sampling technique for selecting the participants. For example, Rama has worry about the result which she is going to obtain during the ’20s would not be applicable to those who were not there in the 20s.

How to measure external validity?

The technique for testing the external validity is to facilitate the investigation again but with different populations or in different situations.

 Difference between internal and external validity

Basis Internal validity External validity


Internal validity is mainly related to the framework of investigation and also to different components of the study.External validity is related to the way the outcome of any research is applicable to other situations.


It demonstrates the formal relation between different components of research.It indicates the generality of the investigation.


Internal reliability in research is highly dependent on the way research perform different processes.


You in order to make your research highly validate will require concentrating on a selection of strong research methodology for performing the study.

It mainly emphasizes representing the gap that has taken place because of a single independent variable.

Here, you will need to concentrate on making the findings of your investigation applicable to other similar situations.


Control on extra variables in the studyControl on a generalization of findings


Warranty is provided for the conclusion.You can Apply the outcome practically.

Factors that could cause risk

Historical Events: Such events might negatively affect the findings of research over a period of time. For instance, changes in political situations.

Instrumentation: It basically includes the instrument which the researcher utilizes for testing the effect on participants.

Replication: It mainly includes conducting an investigation again. But by using different sample sizes or in different situations.

Reprocessing: Such a factor involves utilizing the statistical instruments for making adjustments in issues.

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