3. The Sign Test: A Worked Example

About this Lecture

Lecture

In this lecture, we work through an example of the Sign test, focusing in particular on: (i) the Sign test as a statistical test designed to assess whether there is a difference between two related sets of data; (ii) the two conditions given being that participants are either allowed or not allowed to use social media immediately before going to sleep, and each reporting their sleep quality; (iii) the experimenter’s hypothesis that, based on previous research, those not allowed to use social media immediately before going to bed will report a better quality of sleep; (iv) working through each step in the process of performing a sign test on this set of data and how one might formulate a conclusion, given the results found.

Course

In this course, Dr Alison Wadeley (Bath Spa University) explores the challenging subject of inferential statistics. In the first lecture, we think about the decision tree required to establish which non-parametric test should be used, based on the experimental design and the data being collected. In the second lecture, we think about four example research questions and work through the process of deciding which non-parametric test is appropriate for each, before moving on to parametric tests. In the third lecture, we think about how the sign test is used to assess a research question on sleep quality and social media use. Next, we think about probability, critical values, and significance; helping to unpack the inner workings of these tests. In the fifth and final lecture, we think about the errors that can occur when interpreting results from these tests, how you might recognise them, and what can be done to reduce their prevalence.

Lecturer

Dr Alison Wadeley is a senior lecturer in the Department of Psychology at Bath Spa University, leading undergraduate teaching on psychological research methods and statistics. Dr Wadeley’s own research focuses on how naturally occurring sleep disruption can impact adult cognitive function, as well as ankylosing spondylitis. Dr Wadeley’s recent publications include ‘Real-world experience of secukinumab treatment for ankylosing spondylitis at the Royal National Hospital for Rheumatic Diseases, Bath’ (2020) and ‘Does measuring the bone mineral density of patients identified as having an osteopaenic X-ray appearance affect bone health treatment decisions? A real-world retrospective analysis’ (2019).