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Research Methods – Experimental Methodology

2. Quasi and Natural Experiments

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In this lecture, we think about quasi and natural experiments, focusing in particular on: (i) the field experiment example from lecture one contrasted with these different experiment types; (ii) describing a quasi experiment 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); (iii) why a researcher may choose to run a quasi, rather than a true, experiment, before contrasting it with a natural experiment; (iv) the fact 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 is not involved 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. In the first lecture, we introduce the gold standard of psychological research: the true experiment. In the second lecture, we break down the term ‘experiment’ by highlighting the definitions of quasi and natural experiments. In the third lecture, we think about the commonly practiced experiment alternative, the observational study – a key aspect of a natural experiment. Next, we build on module three by focusing on the self-report methods which are often used in observational studies. In the fifth lecture, we move to the post-procedure aspect of experimentation by approaching correlations and what they mean in the analysis of results. In the sixth lecture, we bring to light content analysis, a lesser studied qualitative method of categorising and analysing experimental results. In the seventh and final lecture, we think about case studies, the divisive method of study which is in equal part invaluable and useless!


Dr Peter Allen is a senior lecturer in the School of Psychological Science at the University of Bristol. Dr Allen’s research interests are in evidence-based learning and teaching in higher education, with a focus 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. Some of Dr Allen’s recent publications include 'Training Structural Awareness with StatHand' (2022) and 'Research Performance of Academic Psychologists in the United Kingdom' (2022).

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APA style

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

MLA style

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

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