Comment on Nalliah and Allareddy (2014): Unwarranted conclusions
- Published
- Accepted
- Subject Areas
- Science and Medical Education, Statistics
- Keywords
- Regression to the mean, Rescaling of data, Data errors
- Copyright
- © 2015 Bernhardt
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2015. Comment on Nalliah and Allareddy (2014): Unwarranted conclusions. PeerJ PrePrints 3:e1191v1 https://doi.org/10.7287/peerj.preprints.1191v1
Abstract
A PeerJ paper by Nalliah and Allareddy (2014) describes improvement in weaker dental students’ scores (and decline in stronger students’ scores) by use of a unique instructional method. I argue that the causal conclusion in their paper cannot be justified because of lack of a comparison group. Regression to the mean is a common confound in test-retest studies such as presented in their paper. Inclusion of a comparison group could be used to rule it out. Other minor issues are raised involving scaling and consistency in the data.
Author Comment
While comments in PeerJ are usually directly posted to the incident article, this is a very lengthy comment raising numerous issues. There are substantial statistical analyses and a Table presented which would tend to preclude the more usual commenting system of PeerJ.