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Statistics for Psychologists – Data and the T-test

1. What are Data?

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In this lecture, we think about types of data, focusing in particular on: (i) data as the cornerstone of all scientific disciplines; (ii) quantitative (or numerical) and qualitative (or categorical) data; (iii) discrete and continuous data as subsets of quantitative data, the former being that which can only be subdivided so much (e.g. the number of houses on a street) and the latter being that which can be continually subdivided (e.g. time); (iv) nominal and ordinal data as subsets of qualitative data, the former being that which has no natural order (e.g. colours) and the latter being that which does (e.g. days of the week); (v) population and sample datasets, using measuring the heights of 17-year-olds in the UK as an example study.


In this course, Dr Andrew Bell (Kings College London) introduces statistics for psychologists and the t-test. In the first lecture, we are introduced to the different types of data which might be analysed for a scientific study. In the second lecture, we think about descriptive statistics, specifically mean, variance, and standard deviation. In the third lecture, we explore data distributions, working through normal (or Gaussian), leftward skewed, and rightward skewed graphs. Next, we think about null hypothesis significance testing (NHST), highlighting the importance of understanding what is meant by rejecting and not rejecting a hypothesis. In the fifth lecture, we think about the t-test, outlining the similarities and differences between a one sample, independent samples, and paired samples test. In the sixth and final lecture, we work through an example of each of the three t-tests to solidify our understanding.


Dr Andrew Bell is a lecturer in cognitive neuroscience in the Institute of Psychiatry, Psychology and Neuroscience at King’s College London. Dr Bell works in the neuroimaging department and focuses his teaching on statistics and statistical techniques. Dr Bell is a senior fellow of the Higher Education Academy and has published a review of animal lesion techniques used by researchers of human neuropsychology. Dr Bell’s recent publications include ‘Preserved extrastriate visual network in a monkey with substantial, naturally occurring damage to primary visual cortex’ (2019) and ‘Viewing ambiguous social interactions increases functional connectivity between frontal and temporal nodes of the social brain’ (2021).

Cite this Lecture

APA style

Bell, A. (2022, February 10). Statistics for Psychologists – Data and the T-test - What are Data? [Video]. MASSOLIT.

MLA style

Bell, A. "Statistics for Psychologists – Data and the T-test – What are Data?." MASSOLIT, uploaded by MASSOLIT, 15 Feb 2022,

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