Posted on: 2nd Apr 2020 2198 Views

External Validity in Research

In the previous article, we have developed an understanding of the concepts of internal validity. Now in this article, we will learn about external validity in research.

External validity is the extent to which the findings of your investigation can be applied to other settings. In this article, our research paper writing team is providing you with a guide for improving the external validity of research results.

External Validity

What is External Validity?

The term “external validity” relates to how effectively a study’s findings can be expected to apply in other situations. In other words, the generalizability of the findings is determined by this form of validity. Are the findings applicable to different persons, contexts, events, or periods, for example?

External validity refers to the extent to which a study’s findings may be applied to other contexts. External validity, in simple terms, indicates that the findings or conclusions gained from your research can be applied to other studies. In terms of external validity, the findings of the study can be applied to other situations.

External validity threats: Factors affecting the external validity

The two important factors which might create a threat to the external validity of research results are:

TestingAbout pre-testing, the behaviour of participants can have a significant influence on research outcomes.The researcher has utilized the questionnaire technique in the pre-test which has influenced participants to think about job satisfaction.



An unrelated occurrence has an impact on the outcome.A natural disaster strikes a neighbouring state just before the pre-test. As a result, anxiety levels before to the test are higher than they could otherwise be.


Biasness in Selection of participantsThe difference in characteristics of the population from where participants are selected.For instance, in earlier studies researchers might have chosen older people as participants.  People participating in the present investigation may be younger.   Therefore, you cannot provide a general conclusion.
The effect of the experimenterThe experimenter’s (s)’ personality or behaviours unintentionally impact the results.The mindfulness session facilitator accidentally emphasized the significance of this study for the research department’s financing.
Effect of HawthorneParticipants’ proclivity to alter their conduct just because they are aware that they are being observed.Because they are aware of their participation in the study, the participants intentionally avoid anxiety-inducing circumstances for the duration of the study.
Aptitude-treatmentThe dependent variable is influenced by interactions between group traits and individual variables.Anxiety levels are reduced when certain characteristics of depressed participants (e.g., negative thought patterns) interact with mindfulness activities (e.g., attention on the present). People with personality disorders or schizophrenia were not able to duplicate the findings.
The impact of the situationThe findings’ generalizability is limited by factors such as the environment, time of day, region, researcher characteristics, and so on.The experiment is repeated with one difference: instead of practising mindfulness in the morning, the volunteers practice it at night.

How do you deal with threats to your external validity?

Threats to external validity can be addressed in several ways:

  • Almost all hazards are mitigated by replications, which increase generalizability to various locations, populations, and situations.
  • The use of natural contexts in field experiments counteracts testing and scenario effects.
  • By ensuring that everyone in a population has an equal chance of being chosen for a study sample, probability sampling prevents selection bias.
  • Recalibration or reprocessing also reduces selection bias in study samples by employing algorithms to alter the weighting of characteristics (such as age).

In addition to the above, the other factors which might influence the external validity of research are situational factors such as characteristics of the population, noise, location, time, etc. All these variables might influence the generalization of findings. In a few cases, characteristics or features of the sample can be responsible for influencing the generalization of findings.

For example, if You conduct research on smoking sensation after one week of issues faced by the general surgeon and the well-publicized results of the latest smoking and cancer studies, you might get different results than if you had done it the week before.

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How to improve external validity?

The different techniques which you can use for improving the external validity of the research results are:

  • Sampling model: You can improve the external validity of research by making the selection of participants very concisely. In simple words by using an appropriate sampling model you can improve the external validity of the research.
  • According to the sampling model, you need to first identify the population which you intend to generalize. After that, you need to select a sample from it and then you can write research with the help of the sample.

The biggest drawback of the sampling approach is that you cannot be sure about the population which you intend to generalize. You might face difficulty in selecting a sample.

For example, you can utilize a random sampling technique for selecting participants. After making the selection of participants you should make sure that all the participants participate in the study.

  • Use the theory of proximal similarity: Another most effective approach which you can apply for improving external validity is the theory of proximal similarity.  According to this approach, you need to describe how your hypothesis differs from others.
  • You for demonstrating the difference between your theory and others, you need to provide a huge amount of information. The huge amount of data will help you in demonstrating a high level of similarities between people, places, etc.
  • Replication of the study: Replication of the study is another best approach that will help you in maintaining your external validity of research results much stronger. It means that you can perform research again by selecting a different sample.
  • You can also facilitate study in a completely new setting.  Many researchers also utilize the Meta-analysis technique for examining whether the influence of the independent variable is reliable or not. Another way is that you can perform studies outside the laboratory.
  • Calibration: You can use statistical techniques for adjusting to problems related to external validity. In case there are uneven groups in your study then reweighting technique.
  • Use of inclusion and exclusion criteria: You can utilize inclusion and exclusion criteria to confirm that the population is clearly defined.
  • Psychological realism: It includes ensuring that all the participants are getting an equal experience. You can provide a good experience to participants by telling them a story and informing them about the purpose of the research.
  • It is considered being as one of the best techniques which cans you can utilize for positively influencing participants to adopt good behaviour throughout the research. The positive attitude of participants is very crucial throughout the study about the generation of accurate outcomes.

External validity is influenced by seven main factors:

  1. Characteristics of the population (subjects)
  2. The relationship between subject selection and research
  3. The independent variable’s descriptive explicitness
  4. The impact of the research setting
  5. Effects of the researcher or the experimenter
  6. Methodology for data collection
  7. Time’s influence


From the above article, it has been concluded that external validity is determined by whether or not findings can be applied to other studies. The sampling method was effective in improving the research’s external validity because of its applicability to many different kinds of studies and experiments.

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