Human cognitive neuroscience seminar
Speaker: Robert McIntosh (University of Edinburgh)
Title: The problem of power in single-case neuropsychology
Abstract: Researchers and clinicians in neuropsychology often compare individual patients against healthy control samples, to quantify evidence for cognitive-behavioural deficits and dissociations. Statistical methods for these comparisons have been developed that control Type I (false positive) errors effectively. However, remark-ably little attention has been given to the power of these tests. In this practical primer, we describe, in minimally technical terms, the origins and limits of power for case-control comparisons. We argue that power calculations can play useful roles in single-case study design and interpretation, and we make suggestions for optimising power in practice. As well as providing figures, tables, and tools for estimating the power of case-control comparisons, we hope to assist researchers in setting realistic expectations for what such tests can achieve in general.
- McIntosh, R. D., & Rittmo, J. Ö. (2020). Power calculations in single case neuropsychology. https://psyarxiv.com/fxz49
- McIntosh, R. D. (2018). Simple dissociations for higher-powered neuropsychology. Cortex, 103, 256-265.
Relevant points of discussion might include the following:
- Does a lack of complete control over power mean that single-case studies are inherently unsuited to study pre-registration?
- Does the chronically low power of case-control comparisons mean that such studies should generally be regarded as exploratory (that is, hypothesis-generating, rather than hypothesis-testing)?
- Is publication bias (towards positive findings) particularly severe for single-case studies, and - if so - what implications does this have?
- How should single-case studies address the issue of alpha correction, if deficits or dissociations have been examined in multiple patients?
- Can the power constraints of single-case studies justify an alpha level (i.e. significance threshold) higher than the conventional .05?
- Should we do away with the traditional distinction between classical and strong dissociations?
The seminars are organised by the Human Cognitive Neuroscience research group. For further information, or if you would like to join the e-mail list for these seminars, please email Mario Cecchini, Elva Peng or Riccardo Sacripante.