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Research Methods – Experimental Methodology

2. Quasi and Natural Experiments

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About this Lecture


This second lecture focuses specifically on quasi and natural experiments, bringing back the field experiment example from lecture one to contrast with these different experiment types. A quasi experiment is described as typically lacking the randomisation element of a true experiment, meaning that it is more difficult to assign a change in the dependent variable to a change in the independent variable (causality). Dr Allen then explains why a researcher may choose to run a quasi, rather than a true, experiment, before contrasting it with a natural experiment. The main point of the latter being that a quasi experiment still involves variable manipulation, unlike a natural experiment.


Quasi Experiment – An empirical intervention study used to estimate the causal impact of an intervention. It resembles a true experiment but lacks proper experimental control which, in practical terms, normally means a lack of randomisation.

Natural Experiment – The researcher has no involvement in the creation or implementation of the independent variable. Instead, the researcher takes advantage of something that is already happening, independent from their own actions.


In this course, Dr Peter Allen (University of Bristol) explores the experimental structure and methodology that underlies much of the research that informs our psychological theories. The first lecture introduces the gold standard in psychological research: the true experiment. The second lecture breaks down the term ‘experiment’ by highlighting the definitions of quasi and natural experiments. The third lecture brings to light the commonly practiced alternative to the experiment, in the form of observational studies – a key aspect of a natural experiment. The fourth lecture builds on lecture three by focusing on the self-report methods which are often used in observational studies. The fifth lecture moves to the post-procedure aspect of experimentation by approaching correlations and what they mean in the analysis of results. The sixth lecture brings to light content analysis, a lesser studied qualitative method of categorising and analysing experimental results. The seventh and final lecture on this course addresses case studies, the divisive method of study which is equal parts invaluable and useless!


Dr Peter Allen is a senior lecturer in the School of Psychological Science at the University of Bristol. In recent years, Dr Allen’s research has centred around evidence-based learning and teaching in higher education. A key focus has been on statistical literacy, specifically on understanding the barriers that psychology students can face when learning research methods and statistics. A goal of this research is to derive strategies that can help students become better researchers and scientific thinkers.

Cite this Lecture

APA style

Allen, P. (2022, January 07). Research Methods – Experimental Methodology - Quasi and Natural Experiments [Video]. MASSOLIT.

MLA style

Allen, Peter. "Research Methods – Experimental Methodology – Quasi and Natural Experiments." MASSOLIT, uploaded by MASSOLIT, 07 Jan 2022,

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