Reflections on regression towards the mean

2012 ◽  
Vol 23 (2) ◽  
pp. 271-274 ◽  
Author(s):  
Ryan D. Tweney
2012 ◽  
Vol 18 (4) ◽  
pp. 387-390 ◽  
Author(s):  
Gary R Cutter

Relapse rates and thus the impact of therapies have been decreasing. Why they decline and the impact on our ability to understand which treatments are better require more than simple math. The objective of this review is to discuss the impact of regression to the mean, changes in outcome effects and how we compare outcomes over time and among studies. This paper provides discourse on the topics of regression to the mean, some examples of the pitfalls of changes and some difficulties in the interpretation of the common percentage change in outcomes. The results show that we can often be deceived by what we think we see and they also demonstrate how such confusion evolves in the literature. This article aims to caution against the over-interpretation of changes from baseline, which are helped along by regression towards the mean and other factors. Furthermore, how we interpret changes from baseline requires care and not wishful thinking, coupled with careful digestion of seemingly reasonable explications of results.


2012 ◽  
Vol 25 (0) ◽  
pp. 13
Author(s):  
David Aagten-Murphy ◽  
Giulia Cappagli ◽  
David Burr

Expert musicians are able to accurately and consistently time their actions during a musical performance. We investigated how musical expertise influences the ability to reproduce auditory intervals and how this generalises to vision in a ‘ready-set-go’ paradigm. Subjects reproduced time intervals drawn from distributions varying in total length (176, 352 or 704 ms) or in the number of discrete intervals within the total length (3, 5, 11 or 21 discrete intervals). Overall musicians performed more veridically than non-musicians, and all subjects reproduced auditory-defined intervals more accurately than visually-defined intervals. However non-musicians, particularly with visual intervals, consistently exhibited a substantial and systematic regression towards the mean of the interval. When subjects judged intervals from distributions of longer total length they tended to exhibit more regression towards the mean, while the ability to discriminate between discrete intervals within the distribution had little influence on subject error. These results are consistent with a Bayesian model which minimizes reproduction errors by incorporating a central tendency prior weighted by the subject’s own temporal precision relative to the current intervals distribution (Cicchini et al., 2012; Jazayeri and Shadlen, 2010). Finally a strong correlation was observed between all durations of formal musical training and total reproduction errors in both modalities (accounting for 30% of the variance). Taken together these results demonstrate that formal musical training improves temporal reproduction, and that this improvement transfers from audition to vision. They further demonstrate the flexibility of sensorimotor mechanisms in adapting to different task conditions to minimise temporal estimation errors.


Gerontology ◽  
2015 ◽  
Vol 62 (2) ◽  
pp. 191-199 ◽  
Author(s):  
Barbara Rubek Nielsen ◽  
Allan Linneberg ◽  
Kaare Christensen ◽  
Julie Lyng Forman ◽  
Peter Schwarz

Background: Epidemiological studies have reported that a higher perceived age is associated with poor health and higher mortality. However, the method used for the assessment of perceived age differs between studies with regard to age, gender, the number and occupation of assessors as well as the presentation of participants. Objective: It is not known whether the clinical experience of the assessor or photographic presentation have an influence on the assessment of perceived age, which the present study aimed to investigate. Methods: In a cross-sectional study of 460 women aged 25-93 years, 10 consultants and 10 residents were asked to estimate the age of each participant using three different photographic presentations: facial photograph, whole-body photograph, and combined facial and whole-body photographs. Data were analyzed by means of summary statistics and linear mixed models. Results: The inter-class correlation coefficient within each assessor group and photographic presentation varied from 0.66 to 0.75. Limits of agreement were in a broad range but were similar in the two assessor groups. The best inter-assessor agreement was obtained from photographs of both the face and the whole body. Intra- and inter-assessor agreements between photographic presentations were similar among both assessor groups. The accuracy in age assessment was significantly influenced by the photographic presentation but not by the clinical experience of the assessor. The difference in the mean perceived age of a participant of average age was estimated as +0.40 years (95% CI: -1.80; 2.59) for consultants versus residents, -2.05 years (95% CI: -2.90; -1.19) for facial photographs versus both facial and whole-body photographs, and -1.44 years (95% CI: -2.30; -0.58) for whole-body photographs versus both facial and whole-body photographs. A regression towards the mean age was seen. Conclusion: The assessment of perceived age was influenced by the photographic presentation but not by the clinical experience of the assessor.


2011 ◽  
Vol 21 (6) ◽  
pp. 762-784 ◽  
Author(s):  
Michael D. Maraun ◽  
Stephanie Gabriel ◽  
Jack Martin

BMJ ◽  
1994 ◽  
Vol 309 (6957) ◽  
pp. 780-780 ◽  
Author(s):  
J M Bland ◽  
D G Altman

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