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Issues and Debates – The Replication Crisis

3. Validity

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About this Lecture


This third lecture discusses validity, focusing on internal and external validity. Validity is defined as effectively ensuring that a study is measuring what it should be measuring, and what the researcher thinks it is measuring. Firstly, Dr Bouguettaya raises some questionable examples of how someone might assess antisocial personality qualities, challenging the internal validity of these proposed measures. To follow, an example of a measure with good internal validity is discussed, contextualised in a study on depression. The second validity type outlined in this lecture, external validity, is discussed in the context of an unintended social experiment in 1985 – ‘New Coke’. Lastly, this lecture provides an example of a study on helping in the event of an emergency with good external validity and applies this logic to psychology as a whole.


Validity – The extent to which a study or measure truly assesses what it intends/claims to.


In this course, Dr Ayoub Bouguettaya (University of Birmingham) explores a key shortcoming in the field of psychological science – replication. The course starts by introducing the concept of replication and defining science in terms of three key criteria: reliable and valid theory which can predict outcomes, theories that can be disproven by quantifiable experimentation, and theories that are altered or withdrawn in the light of new findings. Lecture two explores reliability and outlines three core issues facing psychological science: quantifiable measures, theories that cannot be disproven, and unrefined theories. Lectures three and four explore the definition of validity, its variety of forms, and the challenges associated with formulating valid research. The fifth lecture highlights the interrelatedness of validity and reliability, as well as returning to this idea of replication and the many famous studies which have failed either conceptual or exact replication. The sixth and final lecture addresses the ways in which the field of psychology is tackling these problems and concludes on two different perspectives on whether psychology can be considered a true science.


Dr Ayoub Bouguettaya is a lecturer in the School of Psychology at the University of Birmingham. His research centres around social psychology and how knowledge from that field can be applied to others, particularly health. Dr Bouguettaya is interested in how we can apply social identity theory to societal problems, as well as investigating the different perspectives one might taken on those issues. His recent publications have spanned a breadth of topics including social identification, eating behaviours, conspiracy theories, and behavioural economics.

Cite this Lecture

APA style

Bouguettaya, A. (2021, November 24). Issues and Debates – The Replication Crisis - Validity [Video]. MASSOLIT.

MLA style

Bouguettaya, Ayoub. "Issues and Debates – The Replication Crisis – Validity." MASSOLIT, uploaded by MASSOLIT, 30 Nov 2021,